Since the Wnt pathway is correlated to ABCB1 expression level in multidrug resistant cells [18], the ABCB1, β-catenin, c-Myc and cyclin D1 protein levels were evaluated in the parental uterus sarcoma MES-SA and the breast cancer MCF7 cell lines in relation to their drug resistant counterparts, MES-SA/Dx5 and MCF7/ADR2, respectively. The gene discussed is ABCB1; the disease is breast cancer.