XIAP and cancer: YM155 is a small imidazolium-based compound that has been reported to block the gene expression of survivin/BIRC5 via its promoter inhibition and inhibits XIAP by degradation induction.26, 27, 28 However, the effects of YM155 seem to differ in different cancer models and cellular backgrounds, for example, in some studies it has been shown that YM155 may directly induce DNA damage and that the reduced expression of survivin and XIAP may rather be a consequence of DNA damage due to the interrelationship between these IAP and DNA damage repair pathways.26