PTEN and hepatocellular carcinoma: Besides PTEN, miR-221 and miR-222 also directly regulate the expression of the protein phosphatase 2A subunit B (PPP2R2A) and TIMP3 tumour suppressors, thus activating the AKT pathway and metallopeptidases to promote HCC cell invasion and metastasis (Garofalo et al, 2009; Wong et al, 2010).