SMAD3 and hepatocellular carcinoma: When PAK3 was overexpressed in Huh7 and HepG2 hepatoma cells, the levels of p-Smad2 and p-Smad3 were significantly increased, while the levels of total Smad2 and Smad3 were almost unchanged, suggesting that PAK3 may act through the Smad-dependent TGF-β pathway to promote EMT in hepatoma cells.