SIRT1 and cancer: Interestingly supporting our assumption recent reports suggest, the tumor supresssor gene HIC1 (hypermethylated in Cancer 1) which is widely expressed in healthy tissues but deleted in cancer is activated by DNA double strand breaks and plays a central role in the DNA damage response and DNA repair through the establishment of several complex regulatory loops involving, HIC1, p53, HDAC4, SIRT1 and E2F1[41–43].