PIK3R1 and neoplasm: Of note, in addition to a mutation in the cancer driver Kras [23] we detected two mutations in PI3K subunits Pik3r1 and Pik3ca and a deactivating stop-gain mutation of tumor suppressor Pten, which regulates PI3K by dephosphorylating the lipid signaling intermediate PIP3 to PIP2 [24].