Intriguingly, we observed a drastic decrease in epithelial markers for breast cancer cells such as CLDN4, MUC1, MUC15 or EPCAM, simultaneously accompanied by a notable increase in mesenchymal cell markers including TWIST1/2, VIM, ZEB2, ACTA2, SNAIL2, FN1 and NCAD, supporting EMT induction in the resistant cells compared to their parental counterparts. The gene discussed is CLDN4; the disease is breast cancer.