CAMK2G and leukemia: In particular, radiation-induced Ca2+ signals in glioblastoma and leukemia cells were shown to activate isoforms of the Ca2+/calmodulin-dependent kinase II (CaMKII), which via inactivating phosphorylation of cdc25 phosphatases keeps the cdc2 subunit of the mitose-promoting factor in a phosphorylated and thus inactive form resulting in G2/M cell cycle arrest.