TP53 and colonic neoplasm: these results were indicative of a topotecan-induced cytoprotective role for autophagy in p53 wild type colon cancer cell lines; however, the evidence for cytotoxic and/or nonprotective functions of autophagy in the cell lines lacking functional p53 is reflective of what we have termed the “autophagic switch” [52], where one form/function of autophagy is converted to another when p53 function has been compromised.