Effect of TP53 silencing on the ability of Nutlin-3 to up-regulate Notch1 in leukemic cell lines. OCI cells were either not transfected or transfected with control scrambled (scr) siRNA or p53 siRNA before treatment with Nutlin-3 (10 μM), as indicated. Levels of p53 and Notch1 proteins were assessed by Western blot analysis of cell lysates; tubulin staining is shown as loading control. Representative examples of Western blot results of 3 independent experiments are shown. After densitometric analyses, p53 and Notch1 protein levels were expressed as arbitrary units (au). Data are reported as means ± SD of results from 3 independent experiments.