BMP3 is a TGF-β superfamily member that functions as a negative regulator of bone formation. While historically considered osteogenic, BMP3 actually antagonizes osteogenic BMP signaling rather than promoting bone formation itself 1. BMP3 signals through TGF-β/activin pathways, activating SMAD-dependent cascades that compete with BMP2-induced osteogenesis 1. In vivo, Bmp3-deficient mice exhibit increased trabecular bone, confirming BMP3's inhibitory role in osteogenesis 1. Conversely, BMP3 promotes differentiation of mesenchymal stem cells toward nucleus pulposus-like phenotypes, enhancing cell proliferation and glycosaminoglycan content through TGF-β pathway activation 2. BMP3 is notably the most abundant BMP in demineralized bone matrix, suggesting it modulates osteogenic BMP activity in vivo 1. Beyond skeletal development, aberrant BMP3 promoter methylation serves as a clinical biomarker for colorectal cancer detection 345. Combined BMP3 and SEPT9 methylation analysis in plasma achieves 80% sensitivity and 81% specificity for CRC detection when paired with age assessment 5. Additionally, upregulation of BMP signaling, including BMP3, underlies intrapulpal calcifications in enamel renal syndrome 6.