Knock down of MYC expression decreases activation of ATM, CHK2 and p53.

<p><b>A</b>) HCT116 cells were transfected either with the control GFP-specific (CTR) or MYC specific siRNA for 48h. The expression of MYC was assessed by immunoprecipitation and western-blot analysis. One out of three independent experiments is shown. <b>B</b>) HCT116 cells, transfected either with the GFP-specific (CTR) or MYC specific siRNA were left untreated or exposed to IR (20 Gy), and further incubated in complete medium for the indicated periods of time. The levels of phosphorylation of ATM, CHK2 and p53 were assessed by western blot analysis. Actin and total ATM were used as an internal loading control. One out of three independent experiments is shown.