PTEN and hepatocellular carcinoma: A study on hepatoma cells and hepatic stellate cells in tumor microenvironment showed that hepatocellular carcinoma cells could directly secrete the exosomal miR-21 by targeting PTEN, leading to the activation of PDK1/Akt in HSC, thus further transforming the quiescent hepatic stellate cells into activated cancer associated fibroblasts (CAFs).