Accordingly, we validated the in vitro efficacy of the MEK inhibitor trametinib in the LM9 (p53-mutant), HLE (p53-mutant), and Hep3B (p53-null) human HCC cell lines and the HepG2 (p53-wild type) hepatoblastoma cell line. This evidence concerns the gene TP53 and hepatocellular carcinoma.