Yuan et al. BMC Cancer 2011, 11:57 http://www.biomedcentral.com/1471-2407/11/57 Page 4 of 10 Figure 1 MiR-203 inhibits the proliferation of ESCC cell lines. (A, B) Cell cycle analysis was performed at 48 hr posttransfection by staining DNA with propidium iodide prior to flow cytometry. Results showed that proliferative index (PI) of cells transfected with miR-203 was significantly lower than that of cells transfected with control microRNA. (C, D) Apoptosis assay was performed at 48 hr posttransfection by staining cells with annexin V-FITC and propidium iodide prior to flow cytometry. Results showed that apoptotic index (AI) of cells transfected with miR-203 was significantly higher than that of cells transfected with control microRNA. (E, F) Clonogenic assay was performed as described in materials and methods with cells at 24 hr posttransfection. Results showed that the colony forming efficiency (CFE) of cells transfected with miR-203 was significantly lower than that of cells transfected with control microRNA. (G) Cell population doubling time (PDT) was determined as described in materials and methods with cells at 24 hr posttransfection. Results showed that the PDT of cells transfected with miR-203 was significantly longer than that of cells transfected with control microRNA. Transfection condition: Cells (1 × 106) of Eca109 and TE-1 were transfected with 50 pmol of miR-203 (or control microRNA). Data represent mean ± SEM from 4 independent experiments; *, P < 0.05 by t test. **, P < 0.01 by t test.