TP53 and hepatocellular carcinoma: According to the COSMIC database ATM mutations were found in all 4 tested HCC samples.[7] Preclinical evidence suggested that ATM deficient tumors may be sensitive to PARP inhibitors.[35] Functional loss of TP53 is common in aggressive advanced cancers and is described in detail above (Figure 2).[19] Both A161 and M160 are located within the DNA-binding domain of TP5.