PIK3CA and neoplasm: In HCT116 tumours, the combination of 100 mg/kg GDC-0941 and 1 mg/kg PD 0325901 was shown to inhibit both the MAPK and PI3K pathways, and enhance the inhibition of ERK1/2, S6 and 4EBP1 phosphorylation, compared to either agent alone.