PTK2B and hepatocellular carcinoma: The underlying mechanism may involve the proline-rich tyrosine kinase 2 (Pyk2), which is a target of miR-517a; Pyk2 was shown to promote cell proliferation and invasiveness by upregulation of the c-Src and ERK/MAPK signaling pathways in hepatocellular carcinoma cells (Sun et al., 2008).