PIK3CA and hyperinsulinemic hypoglycemia, familial, 4: PTEN loss on the contrary increases sensitivity to PI3K-AKT and FKBP12-rapamycin associated protein (mTOR) inhibitors via increased S6 kinase activity and phosphorylation of ribosomal S6 protein (38) In addition to several studies involving unselected patient population treated with PI3K/AKT inhibitors and mTOR inhibitors, a selected population with PTEN deficiency is being studied with the experimental drug GSK2636771 (GlaxoSmithKline, London, UK; Table 1).