SMAD2 and hepatocellular carcinoma: TRIM52 up-regulation promoted HCC cell proliferation, migration and invasion in vitro, and down-regulation of TRIM52 inhibited HCC cell invasion, migration and proliferation, induced G0-G1 phase cell cycle arrest in vitro, and inhibited cell growth and Ki67, p-Smad2/3 and MMP2 expression in vivo.