ABCG2 and hepatocellular carcinoma: Further experiments using real-time reverse-transcription quantitative PCR (RT-qPCR) and Western blotting demonstrated that the combination of niclosamide and sorafenib effectively and significantly suppressed both the gene and protein expression levels of pluripotent transcriptional factor OCT4, drug resistance–related ABCG2, and the cell migration–associated IGF-1R in sorafenib-resistant HCC cells (Figure 2B and Supplementary Figure S2B).