We hypothesized that the knockdown of PDCD4 might induce apoptosis in hepatoma cells via the activation of p53 (47), as our present data show that PDCD4 knockdown activates the caspase cascade and induces apoptosis, which was revealed by FACS and TUNEL assays in HepG2 cells containing wild-type p53, while few apoptotic cells were found in Hep3B with null-p53. This evidence concerns the gene TP53 and hepatocellular carcinoma.