TP53 and cancer: In initial attempts to gain antiproliferative mechanistic insights, we conducted cell cycle perturbation studies with a variety of aggressive human cancer cell lines as follows: colon cancer p53 positive HCT116p53+/+ and p53 negative HCT116p53−/− cells, non-small cell lung cancer A549 cells, prostate cancer LNCaP, DU145 and PC3 cells; and to test cancer cell selectivity, we also tested the effects of selected compounds on the cell cycle of normal human fibroblast cells.