DDIT4 and Familial prostate cancer: 9 demonstrated a requirement of REDD1 gene for prostate tumorigenesis and another study 17 reported elevation in REDD1 protein-induced apoptosis in prostate cancer cells. It appears that prostate cells harboring wild-type p53 can upregulate expression of REDD1 in response to DNA damage, whereas in cells with mutated or dysfunctional p53, REDD1 is not targeted. By contrast, exposure of prostate cells to alkylating agents and hypoxia, REDD1 expression is induced by HIF-1α and can negatively regulate mTOR activity in prostate cancer cells.