NCOR1 and hepatocellular carcinoma: Next, to test whether HBX-induced loss of NCoR in HCC positive cells was ubiquitin-proteasome mediated, effect of MG132, a selective inhibitor of proteasome function, on HBX-induced NCoR loss was determined in 293T cells transfected with Flag tagged NCoR and HBX or HCV core plasmids.