PIK3CA and cervical cancer: As shown in Supplementary Figure S5, incubation of cells with 0.5 μM GDC-0941 alone for 24 hours reduced survival by approximately 40% in both CaSki and HeLa-E545K while only reducing survival by about 10% in HeLa cells, suggesting that GDC-0941 is more toxic to cervical cancer cell lines with the PIK3CA-E545K mutation, and consequent misregulated Akt signaling, than cells with endogenous PIK3CA signaling.