SMAD3 and hepatocellular carcinoma: Knockdown of these two integrin subunits significantly suppressed the expressions of N-cadherin, vimentin, α-SMA, p-Smad2, and p-Smad3 in HCC cells grown on higher stiffness substrate, but upregulated E-cadherin expression (Fig. 2i, Additional file 3: Figure S2D).