PIK3CA and cancer: To explore the role of PI3K/AKT activation on cancer cell sensitivity to BRAF and MEK inhibition, we initially reviewed the association of mutations known to activate PI3K/AKT signalling (i.e. oncogenic NRAS and KRAS mutations15), with drug sensitivity data of more than 900 cancer cell lines in the Genomics of Drug Sensitivity in Cancer (GDSC) database.