In MUC4-overexpressing SNU-1196 and SSP-25 cells, GEM IC50 values were downregulated upon HER2 knockdown (Figure 3E-F and S3C-D), suggesting that HER2 increased GEM sensitivity in GEM-resistant sublines and MUC4-overexpressing CCA cells. This evidence concerns the gene MUC4 and cholangiocarcinoma.