Yuan et al. BMC Cancer 2011, 11:57 http://www.biomedcentral.com/1471-2407/11/57 Page 6 of 10 Figure 2 Repressing ΔNp63 expression inhibits proliferation of ESCC cell lines. (A, B) The expression level of ΔNp63 protein was detected by Western Blot at 48 hr posttransfection and normalized to that of b-actin. Results showed that the expression of ΔNp63 protein was significantly decreased in cells transfected with ΔNp63 siRNA as compared to those transfected with control siRNA. (C) The expression level of ΔNp63 mRNA was detected by qRT-PCR at 48 hr posttransfection and normalized to that of GAPDH. Results showed that the expression of ΔNp63 mRNA was significantly decreased in cells transfected with ΔNp63 siRNA as compared to those transfected with control siRNA. (D-G) Cell proliferation was evaluated by cell cycle analysis (D), annexin V-FITC/propidium iodide double staining (E), population doubling time determination (F), and clonogenic assay (G) as described in materials and methods. Results showed that the proliferative capacity of cells transfected with ΔNp63 siRNA was significantly lower than that of cells transfected with control siRNA. Transfection condition: Cells (1 × 106) of Eca109 and TE-1 were transfected with 50 pmol of ΔNp63 siRNA (or control siRNA). Data represent mean ± SEM from 4 independent experiments; *, P < 0.05 by t test. **, P < 0.01 by t test. [13]. These findings suggest that miR-203 might function as a tumor suppressor gene in a variety of tumors. In the case of esophageal cancer, genome-wide microRNA expression profile analysis revealed that the expression level of miR-203 was 2- to 10-fold lower in tumor than in the matched normal tissues [19-21]. However, the effect of miR-203 on the cell proliferation in human ESCC has not been reported. In the present study, we found that the proliferative capacity of ESCC cells transfected with miR-203 was significantly lower than that of cells trans- fected with control microRNA, suggesting that miR-203 could inhibit the proliferative capacity of ESCC cells.