MiR-221 was downregulated in OP and during osteogenic differentiation. A. RT-qPCR was performed to determine the expression levels of miR-221 in patients with osteoporotic fracture and controls showed that miR-221 levels was elevated in bone of OP patients compared with levels observed in non-osteoporotic patients. (P = 0.005). B. RT-qPCR was performed to determine the expression levels of OC, ALP, and COL1A1 in BMP2-induced C2C12 and control cells. *P < 0.05. C. Cells were treated with BMP-2 for 0, 8, 16, and 24 h, and the relative levels of miR-221 to RNU6B were determined by TaqMan MicroRNA expression assay. The control at the 0 h time point was designated as 1. *P < 0.05.