(C) Upper, the linear map of the pRF bicistronic report plasmid. The SV40 promoter (purple box) was used to drive firefly luciferase (Fluc) and Renilla luciferase (Rluc) gene transcription. Different p53 5'UTR fragments were inserted between the Fluc and Rluc genes. Lower, at 24 h after transfection, cells were lysed and luciferase activities were measured using a dual-luciferase kit and the ratio of Fluc/Rluc was calculated. Data shown as means±SD (n=3). Statistical significance was determined by two-tailed Student's t-test. * P<0.01. 