Figure 4. Twist inhibits p53 expression via E-box in the promoter. (A) HepG2 cells were co-transfected p53 promoter with pcDNA (Con) or Myc-tag Twist vector. After 24 h, p53 promoter activity and protein level were determined. (B) HepG2 cells were transfected with luciferase (as a control) or Prox1 shRNA. Protein and mRNA levels of Prox1, Twist and p53 were studied. (C) HepG2 cells were co-transfected human wild type (WT) or E-box mutant of human p53 promoter with pcDNA (Con) or Myc-tagged Twist for 48 h and luciferase activity was determined. Promoter activity of cells co-transfected with pcDNA was defined as 100%. *p < 0.05 when compared with the control group. (D) SK-HEP-1 cells were transfected with wild-type or E-box mutant p53 promoter and promoter activity was determined.