Establishment of cell lines transfected with pcDNA3.1-ING1b or ING1b siRNA. Analysis of ING1b mRNA and protein expression during osteoblast differentiation of C3H10T1/2 mesenchymal stem cells (A) and MC3T3-E1 preosteoblasts (B). Cells were cultured in an osteogenic differentiation medium, and ING1b expression was measured at days 0, 3, 7, and 9 after osteogenic differentiation induction. (C) ALP activity was measured during osteoblast differentiation of C3H10T1/2 mesenchymal stem cells and MC3T3-E1 preosteoblasts using an ALP activity kit. *p < 0.05 versus day 0. Detection of ING1b expression in cells transfected with pcDNA3.1-ING1b or ING1b siRNA by RT-PCR (D) and Western blotting (E). *p < 0.05 versus control. ALP, alkaline phosphatase; ING, inhibitors of growth. RT-PCR, real-time polymerase chain reaction.