RARA and hepatocellular carcinoma: To corroborate the results obtained with the RAR agonists, we evaluated the effects of the RARα antagonist, ER50891 (Kikuchi et al, 2001; Somenzi et al, 2007), and the RARβ/γ antagonist, CD2665 (Szondy et al, 1997), on ATRA-dependent growth inhibition of HCC-1428 and SKBR3 cells, which are characterized by very high ATRA scores.