PTEN and hepatocellular carcinoma: Drug-resistant HCC cells (Bel/5-FU) secrete high levels of exosomal miR-32-5p, and low levels of the tumour suppressor gene PTEN. This discrepancy results from miR-32-5p overexpression, which inhibits PTEN and, subsequently, activates the PI3K/AKT signalling pathway.