The tumor suppressor gene p53 is implicated in most forms of cancer, though the gene itself does not have to be mutated to be ineffective.  Modifications of its protein, from one agent or another, can inactivate its protective effect-as happened in one of the most famous cell lines in history, “HeLa.”  Having animal “knock-out” models for the p53 protein is a great aid to medical researchers, and recently Transposagen Biopharmaceuticals, Inc (Lexington, KY) announced its rat model knockout “TP53.”  This is among some 170 knockouts rats that mimic human diseases.  MORE