In the present study, we have used KLE endometrial carcinoma cell line and HeLa cervical cancer cell line, a widespread model for the study of cancer cell signaling [13,14], to determine the molecular mechanisms responsible for the upregulation of XIAP by each TGF-β isoform, as well as the consequence on XIAP-induced degradation of PTEN. This evidence concerns the gene PTEN and cancer.