AKT1 and neoplasm: Interestingly, the selective sensitivity to AKT inhibition could be attributed to inactivating point mutations in PTEN, a tumor suppressor and negative regulator of the AKT signaling pathway, as the cell lines harboring a mutant PTEN allele [17] were among the most AKT inhibitor-sensitive investigated (Fig. 1d, Supplementary Fig. 2a).