Reduction of cell proliferation after overexpression of RFX1. The human SH-SY5Y cells were transduced with retrovirus carrying the human RFX1 DNA coding sequence or control retrovirus to prepare cells stably overexpressing RFX1 or control cells. A, a representative Western blot image of RFX1 expression in the cells overexpressing RFX1 and control cells. B, quantification of RFX1 mRNA and protein expression. The RFX1 Western blot results were normalized by those of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The RFX1 real-time PCR results were normalized by those of GAPDH and actin. The RFX1 results from the RFX1 overexpressing cells then were normalized by those from control cells. C, cells were cultured in medium without fetal bovine serum for 24 h and then with 10% fetal bovine serum for various times up to 6 days. Cell numbers were measured and normalized by those at the beginning of the fetal bovine serum stimulation. D, cells were cultured in medium without fetal bovine serum for 24 h and then with 10 or 20% fetal bovine serum for 2 days. Cell numbers were then measured and normalized by those at the beginning of fetal bovine serum stimulation. Results are mean ± S.D. (n = 3–6). *, p < 0.05 compared with the corresponding control.