RARA and acute promyelocytic leukemia: By western blot analysis we measured the levels of AKT and its phosphorylation at threonine in position 308 (Thr-308), a marker of AKT protein kinase activation, in primary APL blasts and in PML::RARα + NB4 and PR9 cell lines treated with ATO or with ATO + AKT inhibitor.