Forodesine increases p53 stabilization and induces p53 phosphorylation on Ser15, with the activation of p21. CLL primary cells were incubated with 2 μM forodesine and 10 μM dGuo at different time points, and the expression of p53, the phosphorylation of p53 at Ser15, and the expression of p21 were measured by Western blot and normalized to actin. Western blot data of 2 patients (no. 1 in A; no. 4 in B) are presented.