BMP4 and osteoarthritis: To investigate the involvement of BMP-2 and Wnt/β-catenin signaling pathway in osteoarthritis, we evaluated BMP-2, BMP-4, BMP-7, BMPR-IA, BMPR-IB, LRP-5, LRP-6, phospho-β-catenin, LEF-1, and TCF-4, the major transcription factors of the Wnt canonic signaling pathway expression levels in normal and osteoarthritic chondrocytes.