MLH1 and cancer: Among these genes are MGMT, MLH1, p16/CDKN2A, RASSF1A, PTEN, TP53, p14ARF, AR, WT1, CDH1, p15/CDKN2B, MT1A, and RB1.6,7 The stem cell theory of cancer proposes that cancers arise from stem cells that are present in all tissues.8–10