PTEN and hepatocellular carcinoma: Overexpression of circFN1 can positively regulate the expression of E2F transcription factor 1 (E2F1) by interacting with miR-1205 to achieve sorafenib-resistance in HCC cells, whereas silencing circFN1 can promote the expression of phosphatase and tensin homolog (PTEN) protein and inhibit the activation of AKT in HCC cells, enhancing sorafenib sensitivity in HCC cells (85).