Similar to the G1 phase, the molecular context of CDC25 varies between patients also for this phase, but in contrast to the G1 phase where the heterogeneity is mainly due to the direct effects of AML-associated genetic abnormalities, the heterogeneity of G2 regulation is mainly determined by differences in expression levels (BRCA1, PP2A, PLK1, cyclin B) or isoform profiles (p53, PP2A). The gene discussed is BRCA1; the disease is acute myeloid leukemia.