Figure 6. BMP5 regulates osteoarthritis progression via p38/ERK signaling pathway. (A) Representative western blots show the expression levels of total ERK, p-ERK, total p38, and p-38 proteins in control and BMP5 knockdown chondrocytes mouse chondrocytes treated with IL-1β. (B, D) Representative western blots and quantification show the expression levels of total ERK, p-ERK, total p38, and p-p38 in mouse chondrocytes only treated with different concentrations of rhBMP5(50,100,300ng/ml). (C) Western blot analysis shows the levels of total ERK, p-ERK, total p38, p-p38, p16, cleaved-caspase3, and MMP13 proteins in mouse chondrocytes treated with 100ng/ml rhBMP5, 10 μM PD98059 (MAPK inhibitor) or co-treatment with rhBMP5 and 10 μM PD98059. (E) A schematic working model shows the potential role of Bmp5 in regulating senescence and apoptosis of chondrocytes.