Indeed, it was reported in other types of cancers, such as, for instance, melanoma, non-small-cell lung cancer, small-cell lung cancer, epidermoid carcinoma, and ovarian cancer, that after gemcitabine treatment, cells are characterized by an increase in MDR-1 expression together with the acquisition of more sensitivity to gemcitabine compared to parental cell lines. The gene discussed is ABCB1; the disease is cancer.