PIK3CD and neoplasm: In parallel with mTORC1 activation, constitutively active PI3K stimulates several biological processes that stimulate tumor cell proliferation, such as the Mitogen Activated Protein Kinase (MAPK) and estrogen receptor α (ERα) pathways [20], as well as the reprogramming of glucose and lipid metabolism via AKT activation and AMPK inhibition (Fig. 1) [15, 21].