TP53 and neoplasm: Thus, when p53 is mutated, the three-dimensional structure of p53 is altered and can no longer bind to DNA in a sequence-specific manner to transactivate proteins, including cyclin-dependent kinase (CDK) inhibitors, p21Waf1/Cip1, p53 feedback inhibitor murine double minute 2 (MDM2) [44], the growth arrest and DNA damage-inducible Gadd45a gene, and the BCL-2 family, where apoptosis resistance occurs, thereby reducing the susceptibility of tumor cells to cell death [45,46,47].