PIK3CD and neoplasm: Stimulated by growth factors and other proliferative signals, proliferation-related signaling pathways, such as the RAS, the phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) pathway, and the RAF-mitogen-activated protein kinase (MAPK) kinase (MEK)-extracellular signal-related kinase (ERK) pathway, are activated in tumor cells, which subsequently regulate tumor cell proliferation, migration and invasion, gene transcription, cellular metabolic reprogramming, and tumor microenvironment (TME) remodeling.301–303