<p>(A) Determination of Sp1 effect on the promoter activity of Cyclin D1. C2C12 myoblasts were cotransfected with a reporter containing Cyclin D1 promoter, and Sp1 expression vector (MSCV-Sp1), or control vector (MSCV), or Sp1 specific siRNA (siSp1), or negative control siRNA (NC) as indicated. Error bars represent the SD of three independent experiments. (B and C) Real-time RT-PCR analysis of Sp1 and Cyclin D1 mRNA expression in C2C12 myoblasts transfected with MSCV-Sp1 or MSCV (B), or transfected with siSp1 or NC (C), as indicated. Error bars represent the SD of three independent experiments. (D and E) Western blot analysis of Sp1 and Cyclin D1 protein level in C2C12 myoblasts transfected with siSp1 or NC (D), or MSCV-Sp1 or MSCV.(E). (F and G) Growth curves of C2C12 myoblasts were determined by MTT assay. Cells were transfected with MSCV-Sp1 or MSCV (F), or transfected with siSp1 or NC (G). Error bars represent the SD of three independent experiments. (H) Cell cycle analysis of C2C12 myoblasts transfected with siSp1 or NC as indicated. Data shown are from a typical experiment performed. **p<0.01.</p
