PIK3CD and acute myeloid leukemia: PI3K/Akt/mTOR in AML cells could also be activated by microenvironment-produced factors such as GPCR chemokine receptor type 4 (CXCR4), abundantly expressed on the leukemic cell surface, and its physiological ligand, produced by stromal cells, or β1 integrins on leukemic cells and stromal fibronectin, with upregulation of integrin-linked kinase-1 (ILK1), implicated in integrin-mediated signal transduction by Akt phosphorylation [68].