Finally, Trigueros-Motos et al., [78] used the capecitabine catabolite 5′-deoxy-5-fluorouridine (5′-DFUR) (a nucleoside analog used in the chemotherapy of solid tumors) to demonstrate that AQP3 is required for cytotoxic activity of 5′-DFUR in the breast cancer cell line MCF7 and that this aquaporin is implicated in cell volume increase and cell cycle arrest. The gene discussed is AQP3; the disease is breast cancer.