BIRC5 and cancer: Invariably, the essential function of XIAP and survivin in determining the resistance of cancer cells to apoptosis and subsequently to anti-neoplastic agents were demonstrated in various human malignancies; thus, it appears that downregulation of IAPs may contribute to successful treatment via improving of the sensitivity of cancer cells to chemotherapy and/or radiotherapy mediated by regulation of apoptosis [103, 106–109].