(Q36801625)

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

review article

1 reference

title

Epigenetic drugs as pleiotropic agents in cancer treatment: biomolecular aspects and clinical applications (English)

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

1 reference

2

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Sandra Coral

3

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Alessia Covre

5

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Hugues Nicolay

6

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Luana Calabro'

13

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Michele Maio

14

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

author name string

Luca Sigalotti

1

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Enzo Cortini

4

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Lucia Anzalone

7

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Laura Pezzani

8

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Anna Maria Di Giacomo

9

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Ester Fonsatti

10

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Francesca Colizzi

11

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

Maresa Altomonte

12

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

publication date

1 August 2007

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

Journal of Cellular Physiology

29 December 2019

published in

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

volume

212

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

page(s)

330-344

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

issue

2

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

The in vitro and in vivo effects of re-expressing methylated von Hippel-Lindau tumor suppressor gene in clear cell renal carcinoma with 5-aza-2'-deoxycytidine

29 December 2019

cites work

1 reference

Restoration of transforming growth factor-beta signaling through receptor RI induction by histone deacetylase activity inhibition in breast cancer cells

21 January 2018

1 reference

Induction of transforming growth factor-beta receptor type II expression in estrogen receptor-positive breast cancer cells through SP1 activation by 5-aza-2'-deoxycytidine

21 January 2018

1 reference

Hydralazine target: from blood vessels to the epigenome

21 January 2018

1 reference

Reduced expression of intercellular adhesion molecule-1 in ovarian adenocarcinomas

21 January 2018

1 reference

Methylation of tumor suppressor genes p16(INK4a), p27(Kip1) and E-cadherin in carcinogenesis.

21 January 2018

1 reference

Inactivation of O6-methylguanine-DNA methyltransferase by promoter CpG island hypermethylation in gastric cancers

21 January 2018

1 reference

DNA methylation and gene silencing in cancer

21 January 2018

1 reference

Aberrant methylation of p16(INK4a) is an early event in lung cancer and a potential biomarker for early diagnosis

21 January 2018

1 reference

Antineoplastic action of 5-aza-2'-deoxycytidine and histone deacetylase inhibitor and their effect on the expression of retinoic acid receptor beta and estrogen receptor alpha genes in breast carcinoma cells

21 January 2018

1 reference

Epigenetic reactivation of tumor suppressor genes by a novel small-molecule inhibitor of human DNA methyltransferases.

21 January 2018

1 reference

Methylation-regulated expression of cancer testis antigens in primary effusion lymphoma: immunotherapeutic implications.

21 January 2018

1 reference

Synergy of demethylation and histone deacetylase inhibition in the re-expression of genes silenced in cancer

21 January 2018

1 reference

Enhancement of xenograft tumor radiosensitivity by the histone deacetylase inhibitor MS-275 and correlation with histone hyperacetylation

21 January 2018

1 reference

Sodium butyrate inhibits histone deacetylation in cultured cells

21 January 2018

1 reference

CpG island methylation in aberrant crypt foci of the colorectum

21 January 2018

1 reference

Physical and functional interactions between the human DNMT3L protein and members of the de novo methyltransferase family.

21 January 2018

1 reference

Inhibition of DNA methylation and reactivation of silenced genes by zebularine

21 January 2018

1 reference

Epigenetic regulation by histone methylation and histone variants

21 January 2018

1 reference

Phenotypic and functional changes of human melanoma xenografts induced by DNA hypomethylation: immunotherapeutic implications

21 January 2018

1 reference

Epigenetic inactivation of a RAS association domain family protein from the lung tumour suppressor locus 3p21.3.

21 January 2018

1 reference

Regional hypermethylation and global hypomethylation are associated with altered chromatin conformation and histone acetylation in colorectal cancer

21 January 2018

1 reference

The activation of human gene MAGE-1 in tumor cells is correlated with genome-wide demethylation.

21 January 2018

1 reference

DNA methylation is the primary silencing mechanism for a set of germ line- and tumor-specific genes with a CpG-rich promoter

21 January 2018

1 reference

Inhibition of DNA methylation sensitizes glioblastoma for tumor necrosis factor-related apoptosis-inducing ligand-mediated destruction

21 January 2018

1 reference

Epigenetic lesions causing genetic lesions in human cancer: promoter hypermethylation of DNA repair genes

21 January 2018

1 reference

Generating mutations but providing chemosensitivity: the role of O6-methylguanine DNA methyltransferase in human cancer

21 January 2018

1 reference

MLH1 promoter hypermethylation is associated with the microsatellite instability phenotype in sporadic endometrial carcinomas

21 January 2018

1 reference

Promoter hypermethylation and BRCA1 inactivation in sporadic breast and ovarian tumors

21 January 2018

1 reference

The history of cancer epigenetics

21 January 2018

1 reference

Hypomethylation distinguishes genes of some human cancers from their normal counterparts

21 January 2018

1 reference

DNA methylation and genomic imprinting: insights from cancer into epigenetic mechanisms

21 January 2018

1 reference

Role of estrogen receptor gene demethylation and DNA methyltransferase.DNA adduct formation in 5-aza-2'deoxycytidine-induced cytotoxicity in human breast cancer cells

21 January 2018

1 reference

High frequency of hypermethylation at the 14-3-3 sigma locus leads to gene silencing in breast cancer

21 January 2018

1 reference

Loss of acetylation at Lys16 and trimethylation at Lys20 of histone H4 is a common hallmark of human cancer

21 January 2018

1 reference

Sensitization for death receptor- or drug-induced apoptosis by re-expression of caspase-8 through demethylation or gene transfer

21 January 2018

1 reference

Methylation silencing of the Apaf-1 gene in acute leukemia

21 January 2018

1 reference

Interaction of 5-aza-2'-deoxycytidine and depsipeptide on antineoplastic activity and activation of 14-3-3sigma, E-cadherin and tissue inhibitor of metalloproteinase 3 expression in human breast carcinoma cells

21 January 2018

1 reference

SOCS-1, a negative regulator of cytokine signaling, is frequently silenced by methylation in multiple myeloma

21 January 2018

1 reference

Inactivation of the tissue inhibitor of metalloproteinases-2 gene by promoter hypermethylation in lymphoid malignancies

21 January 2018

1 reference

The 5-methylcytosine content of DNA from human tumors

21 January 2018

1 reference

Histone deacetylase inhibitors: a review of their clinical status as antineoplastic agents.

21 January 2018

1 reference

Phase 1/2 study of the combination of 5-aza-2'-deoxycytidine with valproic acid in patients with leukemia

21 January 2018

1 reference

Epigenetic immunomodulation of hematopoietic malignancies.

21 January 2018

1 reference

Coordinated changes of histone modifications and HDAC mobilization regulate the induction of MHC class II genes by Trichostatin A.

21 January 2018

1 reference

DNA methyltransferase inhibitors-state of the art.

21 January 2018

1 reference

Phase I trial of sequential low-dose 5-aza-2'-deoxycytidine plus high-dose intravenous bolus interleukin-2 in patients with melanoma or renal cell carcinoma.

21 January 2018

1 reference

Histone deacetylase (HDAC) inhibitor activation of p21WAF1 involves changes in promoter-associated proteins, including HDAC1

21 January 2018

1 reference

De novo induction of a cancer/testis antigen by 5-aza-2'-deoxycytidine augments adoptive immunotherapy in a murine tumor model.

21 January 2018

1 reference

Reduced expression of insulin-like growth factor binding protein-3 and its promoter hypermethylation in human hepatocellular carcinoma

21 January 2018

1 reference

The role of DNA methylation in setting up chromatin structure during development

21 January 2018

1 reference

Silencing of the VHL tumor-suppressor gene by DNA methylation in renal carcinoma

21 January 2018

1 reference

Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma

21 January 2018

1 reference

Biochemistry and biology of mammalian DNA methyltransferases

21 January 2018

1 reference

Effect of histone deacetylase inhibitor LAQ824 on antineoplastic action of 5-Aza-2'-deoxycytidine (decitabine) on human breast carcinoma cells

21 January 2018

1 reference

Identification of novel target genes by an epigenetic reactivation screen of renal cancer

21 January 2018

1 reference

Optimizing therapy with methylation inhibitors in myelodysplastic syndromes: dose, duration, and patient selection.

21 January 2018

1 reference

Phase 1 study of low-dose prolonged exposure schedules of the hypomethylating agent 5-aza-2'-deoxycytidine (decitabine) in hematopoietic malignancies

21 January 2018

1 reference

Frequent hypermethylation of 5' flanking region of TIMP-2 gene in cervical cancer

21 January 2018

1 reference

Histone deacetylase inhibitors in cancer therapy: is transcription the primary target?

21 January 2018

1 reference

Monoclonal antibody MA454 reveals a heterogeneous expression pattern of MAGE-1 antigen in formalin-fixed paraffin embedded lung tumours

21 January 2018

1 reference

Toxicity of 5-aza-2'-deoxycytidine to mammalian cells is mediated primarily by covalent trapping of DNA methyltransferase rather than DNA demethylation

21 January 2018

1 reference

Essential role for de novo DNA methyltransferase Dnmt3a in paternal and maternal imprinting

21 January 2018

1 reference

Results of decitabine (5-aza-2'deoxycytidine) therapy in 130 patients with chronic myelogenous leukemia

21 January 2018

1 reference

Decitabine improves patient outcomes in myelodysplastic syndromes: results of a phase III randomized study

21 January 2018

1 reference

Epigenomic profiling reveals novel and frequent targets of aberrant DNA methylation-mediated silencing in malignant glioma.

21 January 2018

1 reference

Depsipeptide inhibits migration of primary and metastatic uveal melanoma cell lines in vitro: a potential strategy for uveal melanoma

21 January 2018

1 reference

Genomic DNA methylation: the mark and its mediators

21 January 2018

1 reference

Promoter methylation and silencing of the tissue factor pathway inhibitor-2 (TFPI-2), a gene encoding an inhibitor of matrix metalloproteinases in human glioma cells.

21 January 2018

1 reference

Cytidine methylation of regulatory sequences near the pi-class glutathione S-transferase gene accompanies human prostatic carcinogenesis

21 January 2018

1 reference

Frequent CpG island methylation in precursor lesions and early gastric adenocarcinomas.

21 January 2018

1 reference

Effects of methylation on expression of TMS1/ASC in human breast cancer cells

21 January 2018

1 reference

Methylation and silencing of the Thrombospondin-1 promoter in human cancer.

21 January 2018

1 reference

Targeting histone deacetylase in cancer therapy

21 January 2018

1 reference

Histone deacetylase inhibitors: multifunctional anticancer agents.

21 January 2018

1 reference

Functional epigenomics identifies genes frequently silenced in prostate cancer

21 January 2018

1 reference

Acetylation of p53 augments its site-specific DNA binding both in vitro and in vivo

21 January 2018

1 reference

Regulation of high molecular weight-melanoma associated antigen (HMW-MAA) gene expression by promoter DNA methylation in human melanoma cells

21 January 2018

1 reference

Epigenetic targets for immune intervention in human malignancies

21 January 2018

1 reference

5' CpG island methylation is associated with transcriptional silencing of the tumour suppressor p16/CDKN2/MTS1 in human cancers.

21 January 2018

1 reference

Human high molecular weight melanoma-associated antigen (HMW-MAA) mimicry by mouse anti-idiotypic monoclonal antibody MK2-23: induction of humoral anti-HMW-MAA immunity and prolongation of survival in patients with stage IV melanoma

21 January 2018

1 reference

Epigenetic therapy of cancer with 5-aza-2'-deoxycytidine (decitabine).

21 January 2018

1 reference

Epigenetic reprogramming in mammals

21 January 2018

1 reference

Vorinostat, a histone deacetylase inhibitor, enhances the response of human tumor cells to ionizing radiation through prolongation of gamma-H2AX foci

21 January 2018

1 reference

Histone deacetylase inhibitors upregulate death receptor 5/TRAIL-R2 and sensitize apoptosis induced by TRAIL/APO2-L in human malignant tumor cells

21 January 2018

1 reference

5-aza-2'-deoxycytidine restores the E-cadherin system in E-cadherin-silenced cancer cells and reduces cancer metastasis

21 January 2018

1 reference

DNA hypermethylation is a mechanism for loss of expression of the HLA class I genes in human esophageal squamous cell carcinomas

21 January 2018

1 reference

De novo DNA methyltransferases Dnmt3a and Dnmt3b primarily mediate the cytotoxic effect of 5-aza-2'-deoxycytidine.

21 January 2018

1 reference

Methylation status of uPA promoter as a molecular mechanism regulating prostate cancer invasion and growth in vitro and in vivo

21 January 2018

1 reference

Identification and functional significance of genes regulated by structurally different histone deacetylase inhibitors

21 January 2018

1 reference

CpG methylation, chromatin structure and gene silencing-a three-way connection

21 January 2018

1 reference

Genomic imprinting: parental influence on the genome

21 January 2018

1 reference

Overcoming resistance to interferon-induced apoptosis of renal carcinoma and melanoma cells by DNA demethylation

21 January 2018

1 reference

Expression of RASSF1A, an epigenetically silenced tumor suppressor, overcomes resistance to apoptosis induction by interferons

21 January 2018

1 reference

Histone deacetylase inhibitor selectively induces p21WAF1 expression and gene-associated histone acetylation

21 January 2018

1 reference

The human ARF cell cycle regulatory gene promoter is a CpG island which can be silenced by DNA methylation and down-regulated by wild-type p53.

21 January 2018

1 reference

5' CpG island hypermethylation is associated with transcriptional silencing of the p21(CIP1/WAF1/SDI1) gene and confers poor prognosis in acute lymphoblastic leukemia

21 January 2018

1 reference

Superiority of prolonged low-dose azanucleoside administration? Results of 5-aza-2'-deoxycytidine retreatment in high-risk myelodysplasia patients.

21 January 2018

1 reference

Histone deacetylase inhibitors profoundly decrease proliferation of human lymphoid cancer cell lines.

21 January 2018

1 reference

Evaluation of a 7-day continuous intravenous infusion of decitabine: inhibition of promoter-specific and global genomic DNA methylation

21 January 2018

1 reference

Changes in DNA methylation in neoplasia: pathophysiology and therapeutic implications.

21 January 2018

1 reference

Effects of 5-aza-2'-deoxycytidine on matrix metalloproteinase expression and pancreatic cancer cell invasiveness

21 January 2018

1 reference

Epigenetic inactivation of TFPI-2 as a common mechanism associated with growth and invasion of pancreatic ductal adenocarcinoma.

21 January 2018

1 reference

Epigenetic inactivation of class II transactivator (CIITA) is associated with the absence of interferon-gamma-induced HLA-DR expression in colorectal and gastric cancer cells.

21 January 2018

1 reference

5-Aza-2'-deoxycytidine induces p21WAF expression by demethylation of p73 leading to p53-independent apoptosis in myeloid leukemia.

21 January 2018

1 reference

Targeting the epigenome for the treatment and prevention of lung cancer

21 January 2018

1 reference

Phase I study of decitabine-mediated gene expression in patients with cancers involving the lungs, esophagus, or pleura

21 January 2018

1 reference

Global DNA hypermethylation-associated cancer chemotherapy resistance and its reversion with the demethylating agent hydralazine

21 January 2018

1 reference

Rexpression of HLA class I antigens and restoration of antigen-specific CTL response in melanoma cells following 5-aza-2'-deoxycytidine treatment

21 January 2018

1 reference

Restoration of tamoxifen sensitivity in estrogen receptor-negative breast cancer cells: tamoxifen-bound reactivated ER recruits distinctive corepressor complexes

21 January 2018

1 reference

Alteration of the methylation status of tumor-promoting genes decreases prostate cancer cell invasiveness and tumorigenesis in vitro and in vivo.

21 January 2018

1 reference

Discovery of two novel, small-molecule inhibitors of DNA methylation

21 January 2018

1 reference

Promoter methylation controls the expression of MAGE2, 3 and 4 genes in human cutaneous melanoma.

21 January 2018

1 reference

5-Aza-2'-deoxycytidine (decitabine) treatment of hematopoietic malignancies: a multimechanism therapeutic approach?

21 January 2018

1 reference

Intratumor heterogeneity of cancer/testis antigens expression in human cutaneous melanoma is methylation-regulated and functionally reverted by 5-aza-2'-deoxycytidine.

21 January 2018

1 reference

Epigenetic modulation of solid tumors as a novel approach for cancer immunotherapy

21 January 2018

1 reference

Inactivation of the apoptosis effector Apaf-1 in malignant melanoma

21 January 2018

1 reference

Sequential 5-Aza 2'-deoxycytidine/depsipeptide FK228 treatment induces tissue factor pathway inhibitor 2 (TFPI-2) expression in cancer cells.

21 January 2018

1 reference

The language of covalent histone modifications

21 January 2018

1 reference

Functional diversity of DNA methyltransferase inhibitors in human cancer cell lines.

21 January 2018

1 reference

Involvement of the tumor necrosis factor (TNF)/TNF receptor system in leukemic cell apoptosis induced by histone deacetylase inhibitor depsipeptide (FK228).

21 January 2018

1 reference

A genomic screen for genes upregulated by demethylation and histone deacetylase inhibition in human colorectal cancer

21 January 2018

1 reference

Epigenetic inactivation of SFRP genes allows constitutive WNT signaling in colorectal cancer

21 January 2018

1 reference

Decitabine activates specific caspases downstream of p73 in myeloid leukemia

21 January 2018

1 reference

Genetic and epigenetic alterations of RB2/p130 tumor suppressor gene in human sporadic retinoblastoma: implications for pathogenesis and therapeutic approach

21 January 2018

1 reference

Crystal structure of a eukaryotic zinc-dependent histone deacetylase, human HDAC8, complexed with a hydroxamic acid inhibitor

21 January 2018

1 reference

Analysis of methylation-sensitive transcriptome identifies GADD45a as a frequently methylated gene in breast cancer.

21 January 2018

1 reference

Chromosome-wide and promoter-specific analyses identify sites of differential DNA methylation in normal and transformed human cells

21 January 2018

1 reference

BRCA1 promoter methylation in sporadic breast cancer is associated with reduced BRCA1 copy number and chromosome 17 aneusomy

21 January 2018

1 reference

Sequential 5-Aza-2 deoxycytidine-depsipeptide FR901228 treatment induces apoptosis preferentially in cancer cells and facilitates their recognition by cytolytic T lymphocytes specific for NY-ESO-1.

21 January 2018

1 reference

Induction of MAGE-3 expression in lung and esophageal cancer cells

21 January 2018

1 reference

DNA methylation and breast carcinogenesis.

21 January 2018

1 reference

DNA hypomethylation and ovarian cancer biology.

21 January 2018

1 reference

Promoter demethylation and histone acetylation mediate gene expression of MAGE-A1, -A2, -A3, and -A12 in human cancer cells

21 January 2018

1 reference

Transcriptional regulation of urokinase (uPA) gene expression in breast cancer cells: role of DNA methylation

21 January 2018

1 reference

Cytosine methylation and the ecology of intragenomic parasites

21 January 2018

1 reference

Dihydro-5-azacytidine in malignant mesothelioma. A phase II trial demonstrating activity accompanied by cardiac toxicity. Cancer and Leukemia Group B.

21 January 2018

1 reference

Epigenetic therapy of cancer: past, present and future

21 January 2018

1 reference

Hypermethylation and silencing of the putative tumor suppressor Tazarotene-induced gene 1 in human cancers

21 January 2018

1 reference

Hypermethylation of the retinoic acid receptor-beta(2) gene in head and neck carcinogenesis.

21 January 2018

1 reference

Clinical evaluation of E-cadherin expression and its regulation mechanism in epithelial ovarian cancer

21 January 2018

1 reference

Lack of phosphotyrosine phosphatase SHP-1 expression in malignant T-cell lymphoma cells results from methylation of the SHP-1 promoter

21 January 2018

1 reference

Histone deacetylase inhibitors FK228, N-(2-aminophenyl)-4-[N-(pyridin-3-yl-methoxycarbonyl)amino- methyl]benzamide and m-carboxycinnamic acid bis-hydroxamide augment radiation-induced cell death in gastrointestinal adenocarcinoma cells

21 January 2018

1 reference

Acetylation of p53 at lysine 373/382 by the histone deacetylase inhibitor depsipeptide induces expression of p21(Waf1/Cip1).

21 January 2018

1 reference

Zebularine: A Novel DNA Methylation Inhibitor that Forms a Covalent Complex with DNA Methyltransferases

21 January 2018

1 reference

5-aza-2'-deoxycytidine activates the p53/p21Waf1/Cip1 pathway to inhibit cell proliferation.

21 January 2018

1 reference

Prolonged Upregulation of the Expression of HLA Class I Antigens and Co stimulatory Molecules on Melanoma Cells Treated with 5-aza-2??-deoxycytidine (5-AZA-CdR)

21 January 2018

1 reference

21 January 2018

Identifiers

DOI

10.1002/JCP.21066

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:17458893%20AND%20SRC:MED&resulttype=core&format=json

29 December 2019

1 reference