PTEN and neoplasm: Hypoxic tumor-derived exosomes suppress the immune system by regulating immune cells, such as macrophages, via the transfer of let-7a miRNA, which inhibits the insulin-Akt-mTOR (mammalian target of rapamycin) signaling pathway [24], promotes MDSCs via the miR-10a/Rora and miR-21/PTEN pathways [56], and impedes T-cell function via exosomal miR-24-3p-mediated target the fibroblast growth factors 11 (FGF 11) [57], among others, as detailed later in the review.