Expression profiles of miR-23b and osteogenesis-associated genes during the early stages of BMP9-induced osteogenic differentiation of C2C12 myoblasts. (A) C2C12 myoblast cell lines were stimulated to undergo osteoblast differentiation using BMP9. RT-qPCR was used to examine the expression levels of miR-23b, which were normalized to U6 as a control. The data demonstrated that miR-23b was reduced over seven days. (B–D) Cells underwent the same treatment as in (A), then were collected at 0, 3 and 7 days. The expression levels of (B) ALP, (C) OCN and (D) OPN were evaluated by RT-qPCR. n=3, *P<0.05, vs. 0 day. (E) RT-qPCR detected the expression of Runx2 in BMP9-induced C2C12 myoblasts over 7 days. miR-23b, microRNA-23b; BMP9, bone morphogenetic protein 9; RT-qPCR, reverse transcription-quantitative polymerase chain reaction; ALP, alkaline phosphatase; OCN, osteocalcin; OPN, osteopontin; Runx2, runt-related transcription factor 2.