SOS2 and hepatocellular carcinoma: Although no SEs could be found at the SOS2 gene locus, the ChIP-Seq signals for H3K27ac were found to be decreased at the typical enhancers (TEs) in the SOS2 gene and at the SEs of HSPB1 as a control, which has been shown to promote oncogene addiction in many types of cancer including HCC, whereas RARα increased the binding to such loci in SOS2 and HSPB1 in sulfarotene-treated TRCs (Fig. 5i, j).