AKT1 and neoplasm: These data are consistent with homozygous and hemizygous alterations that ablate or reduce PTEN protein resulting in a reduced response to PI3Kαi but not to AKTi alone and in combination with fulvestrant, and inhibition of AKT being effective in tumours harbouring PIK3CA mutations regardless of PTEN protein expression (Fig. 3C and Supplementary Fig. 1A).