PAK1 and hepatocellular carcinoma: We demonstrated that PAK1 expression was negatively correlated with not only the survival of HCC patients but also HCC cell response to Sorafenib treatment (high PAK1 activity reduced the inhibitory effect of Sorafenib on HCC cells), and that the anticancer effect of ATRA alone or in combination with Sorafenib was associated with the downregulation of PAK1.