Decitabine treatment delays tumor formation in vivo. (A) iMyc^Eμ mice were bred to p53 knockout mice to produce offspring that were Myc-transgenic and heterozygous for p53. These mice exhibited an accelerated course of disease (median survival 48 days) compared with the iMyc^Eμ mice previously born in the laboratory (dashed line, median survival 198 days). The survival curves and the statistical analyses were performed using the Survival curve function of the GraphPad Prism software (San Diego, CA). (B) Tumors arising in iMyc^Eμ; p53^+/− mice were frozen down as live cells, but pieces were also snap frozen for analyses. The snap frozen tumor pieces were analyzed for their p53 status by PCR genotyping and Western blot analysis (WB). In the PCR, intensities between the top mutant and the bottom wild-type bands were compared with assess loss of heterozygosity (LOH). High amount of p53 protein on the WB indicates mutant protein (*). (C) Vials of live cells were thawed, and the tumor cells were transplanted into the tail veins of 12 recipient C57/BL6 mice. One week after transplant, 6 mice were treated with 3 injections of 5 mg/kg decitabine with 8-hour intervals. The survival curve was generated and analyzed using GraphPad Prism and is a representative of transplantation experiments of 3 different tumors. (D) Tumors arising in transplanted mice were analyzed for the expression of c-Myc protein levels by Western blot analysis.