RARA and hepatocellular carcinoma: The overexpression of GSK-3β in hepatocellular carcinoma cells (HCC) reduces RARβ expression and induces the phosphorylation (Ser 78 and Thr 82 based on human sequence) level of RXRα (using anti-phospho-serine and threonine antibodies) via direct interaction, which is thought to disrupt the formation of dimer with RARα on RARβ promoter, reduce RXR/RAR-mediated transcription, and promote HCC cell clonal formation [123].