CaMKII-mediated inhibitory phosphorylation of cdc25 phosphatases [cdc25B in K562 CML (Palme et al., 2013) and Jurkat T cell leukemia (Klumpp et al., 2016), and probably cdc25C in glioblastoma cells (Klumpp et al., 2017)] prevents the activating dephosphorylation of the cdc25 target p-(Tyr15)-cdc2 as also observed in the present study. This evidence concerns the gene CDC25B and T-cell leukemia.