PTEN and gastric cancer: Conversely, miR-21 is transferred from M2-macrophage to gastric cancer cells through exosomes and inhibits apoptosis of gastric cancer cells by regulating PTEN/phosphoinositide-3-kinase regulatory subunit 1 (Pik3r1, also known as PI3K)/Akt signaling and anti-apoptotic Bcl2 expression [152].