Similarly, using MMTV-Wnt1 mammary tumors (expressing both ER and VDR) in a murine model, it was shown that calcitriol was able to inhibit BCSCs self-renewal and tumor spheroid formation dose-dependently and that the combination of calcitriol with ionizing radiation inhibited spheroid formation to a greater extent than either treatment alone [64]. The gene discussed is ESR1; the disease is breast cancer.