The cancer cells of CASP3/DR to escape from apoptosis often up-regulate the structurally and functionally similar caspase-7 (CASP7) to achieve cellular homeostasis, which can then be inhibited by X-linked inhibitor of apoptosis protein (XIAP) via protein-protein interaction (PPI), leading to accumulation of the XIAP:CASP7 complex [14]. This evidence concerns the gene XIAP and cancer.