PTEN and hepatocellular carcinoma: MiR-21 can promote the proliferation and metastasis of HCC cells by inhibiting the PTEN expression (Meng et al., 2007), reversion inducing cysteine-rich protein with kazal motifs (RECK) and human sulphatase-1 (Sulf-1) (Bao et al., 2013) and can induce resistance at chemotherapeutic drugs in HCC cells (He et al., 2015).