PIK3CA and melanoma: Further, although loss of NF1 and PTEN in melanoma cells is associated with PI3K/AKT activation, these cells remain dependent on MAPK signalling, rather than PI3K/AKT activity for proliferation11,12 and this coincides with equivalent response rates in NRAS-mutant and BRAF-mutant melanoma patients treated with the MEK inhibitor binimetinib13.