This result was further supported by western blotting analysis in MCF-7, T47-D, ZR-75-1, MDA-MB-453, SKBR3, SUM-159, MDA-MB-435, MDA-MB-231 and LM2 breast cancer cells, which demonstrated co-expression of ER and these three factors at the protein level (Figure 5C). The gene discussed is ESR1; the disease is breast cancer.