It has been reported that Exo-miR-21 not only regulates the expression of PTEN, PTENp1, and TETs directly but also increases the methylation level of the PTENp1 promoter by regulating the expression of TETs, which inhibits the expression of PTENp1 and PTEN, promotes the proliferation and migration of HCC cells, and inhibits their apoptosis. Here, PTEN is linked to hepatocellular carcinoma.