PTEN and hepatocellular carcinoma: Resistance to 5-fluorouracil (5-FU) is the main cause of chemotherapy failure in advanced hepatocellular carcinoma, and ROSI activation of PPARγ increases PTEN expression and decreases COX-2 expression, inducing sensitivity to 5-FU antitumor activity in HCC cell lines (Cao et al., 2009).