(Q37222697)

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

title

BMP signaling negatively regulates bone mass through sclerostin by inhibiting the canonical Wnt pathway (English)

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

4

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

author name string

Nobuhiro Kamiya

1

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

Ling Ye

2

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

Tatsuya Kobayashi

3

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

Mitsuo Yamauchi

5

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

Henry M Kronenberg

6

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

Jian Q Feng

7

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

Yuji Mishina

8

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

language of work or name

English

0 references

publication date

16 October 2008

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

number of pages

11

1 reference

inferred from page(s)

published in

Development

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

volume

135

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

issue

22

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

page(s)

3801-3811

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

Disruption of BMP signaling in osteoblasts through type IA receptor (BMPRIA) increases bone mass.

24 December 2019

cites work

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Osteocyte-derived sclerostin inhibits bone formation: its role in bone morphogenetic protein and Wnt signaling.

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A novel transgenic mouse model to study the osteoblast lineage in vivo

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Attenuation of WNT signaling by DKK-1 and -2 regulates BMP2-induced osteoblast differentiation and expression of OPG, RANKL and M-CSF

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Murine and chicken chondrocytes regulate osteoclastogenesis by producing RANKL in response to BMP2

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Endochondral ossification: how cartilage is converted into bone in the developing skeleton.

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Genetic analysis of the roles of BMP2, BMP4, and BMP7 in limb patterning and skeletogenesis

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Wnt signaling: a key regulator of bone mass

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Wnt but not BMP signaling is involved in the inhibitory action of sclerostin on BMP-stimulated bone formation

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Molecular bases of the regulation of bone remodeling by the canonical Wnt signaling pathway.

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Regulation of bone mass by Wnt signaling

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A recurrent mutation in the BMP type I receptor ACVR1 causes inherited and sporadic fibrodysplasia ossificans progressiva

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A Wnt canon orchestrating osteoblastogenesis

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Sclerostin is a delayed secreted product of osteocytes that inhibits bone formation

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

SOST is a ligand for LRP5/LRP6 and a Wnt signaling inhibitor

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Canonical Wnt signaling in differentiated osteoblasts controls osteoclast differentiation

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Essential role of beta-catenin in postnatal bone acquisition

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bmpr1a and Bmpr1b have overlapping functions and are essential for chondrogenesis in vivo

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Sclerostin binds to LRP5/6 and antagonizes canonical Wnt signaling

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bone morphogenetic proteins

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Sclerostin inhibition of Wnt-3a-induced C3H10T1/2 cell differentiation is indirect and mediated by bone morphogenetic proteins

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Wnt/beta-catenin signaling is sufficient and necessary for synovial joint formation

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bone morphogenetic protein type IA receptor signaling regulates postnatal osteoblast function and bone remodeling

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Sclerostin is an osteocyte-expressed negative regulator of bone formation, but not a classical BMP antagonist

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Osteocyte control of bone formation via sclerostin, a novel BMP antagonist

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Wise, a context-dependent activator and inhibitor of Wnt signalling

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

High bone mass in mice expressing a mutant LRP5 gene

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Developmental regulation of the growth plate

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Six novel missense mutations in the LDL receptor-related protein 5 (LRP5) gene in different conditions with an increased bone density

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Ectodermal Wnt3/beta-catenin signaling is required for the establishment and maintenance of the apical ectodermal ridge

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A 52-kb deletion in the SOST-MEOX1 intergenic region on 17q12-q21 is associated with van Buchem disease in the Dutch population

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

High bone density due to a mutation in LDL-receptor-related protein 5

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Efficient recombination in diverse tissues by a tamoxifen-inducible form of Cre: a tool for temporally regulated gene activation/inactivation in the mouse

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Analysis of Relative Gene Expression Data Using Real-Time Quantitative PCR and the 2−ΔΔCT Method

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Identification of a 52 kb deletion downstream of the SOST gene in patients with van Buchem disease

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A mutation in the LDL receptor-related protein 5 gene results in the autosomal dominant high-bone-mass trait

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

beta-Catenin controls hair follicle morphogenesis and stem cell differentiation in the skin

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Increased bone density in sclerosteosis is due to the deficiency of a novel secreted protein (SOST)

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bone dysplasia sclerosteosis results from loss of the SOST gene product, a novel cystine knot-containing protein

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Multiple roles for activated LEF/TCF transcription complexes during hair follicle development and differentiation

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Advances in the osteoblast lineage

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

The head inducer Cerberus is a multifunctional antagonist of Nodal, BMP and Wnt signals

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Generalized lacZ expression with the ROSA26 Cre reporter strain

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Modification of gene activity in mouse embryos in utero by a tamoxifen-inducible form of Cre recombinase

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Osteoprotegerin: a novel secreted protein involved in the regulation of bone density

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Mice deficient for BMP2 are nonviable and have defects in amnion/chorion and cardiac development

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A human chondrodysplasia due to a mutation in a TGF-beta superfamily member

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Two distinct osteoblast-specific cis-acting elements control expression of a mouse osteocalcin gene

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Separate cis-acting DNA elements of the mouse pro-alpha 1(I) collagen promoter direct expression of reporter genes to different type I collagen-producing cells in transgenic mice

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bone morphogenetic protein-4 is required for mesoderm formation and patterning in the mouse

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bone: formation by autoinduction

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

BMP-2 controls alkaline phosphatase expression and osteoblast mineralization by a Wnt autocrine loop

6 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Sclerostin is a novel secreted osteoclast-derived bone morphogenetic protein antagonist with unique ligand specificity

14 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Activated beta-catenin induces osteoblast differentiation of C3H10T1/2 cells and participates in BMP2 mediated signal transduction

14 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Targeted deletion of the sclerostin gene in mice results in increased bone formation and bone strength

14 September 2017

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

BMP2 activity, although dispensable for bone formation, is required for the initiation of fracture healing.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Beta-catenin signaling pathway is crucial for bone morphogenetic protein 2 to induce new bone formation.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

A dishevelled-1/Smad1 interaction couples WNT and bone morphogenetic protein signaling pathways in uncommitted bone marrow stromal cells.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Generation of a mouse with conditionally activated signaling through the BMP receptor, ALK2.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Canonical Wnt signaling negatively regulates branching morphogenesis of the lung and lacrimal gland.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

BMP signaling inhibits intestinal stem cell self-renewal through suppression of Wnt-beta-catenin signaling

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Unique regulation of SOST, the sclerosteosis gene, by BMPs and steroid hormones in human osteoblasts

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Spaciotemporal association and bone morphogenetic protein regulation of sclerostin and osterix expression during embryonic osteogenesis

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Generation of Bmpr/Alk3 conditional knockout mice.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Use of type I collagen green fluorescent protein transgenes to identify subpopulations of cells at different stages of the osteoblast lineage.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bone morphogenetic protein 2 stimulates osteoclast differentiation and survival supported by receptor activator of nuclear factor-kappaB ligand

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Bmpr encodes a type I bone morphogenetic protein receptor that is essential for gastrulation during mouse embryogenesis.

3 September 2018

1 reference

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pmc&linkname=pmc_refs_pubmed&retmode=json&id=2694443

Cell fate specification and competence by Coco, a maternal BMP, TGFbeta and Wnt inhibitor

3 September 2018

1 reference

12 December 2020

Regulation of bone formation and vision by LRP5

1 reference

12 December 2020

TOPGAL mice show that the canonical Wnt signaling pathway is active during bone development and growth and is activated by mechanical loading in vitro

1 reference

12 December 2020

Bone morphogenetic proteins in bone stimulate osteoclasts and osteoblasts during bone development

1 reference

12 December 2020

Bone morphogenetic protein signaling inhibits hair follicle anagen induction by restricting epithelial stem/progenitor cell activation and expansion

1 reference

12 December 2020

Eating bone or adding it: the Wnt pathway decides

1 reference

12 December 2020

Identifiers

DOI

10.1242/DEV.025825

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

1 reference

https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18927151%20AND%20SRC:MED&resulttype=core&format=json

24 December 2019

PubMed publication ID

18927151

1 reference