To assess the putative stimulatory effect of RANKL in RANK-expressing (RANK+) breast and prostate cancer cells, three breast cancer cell lines with different metastatic abilities, MCF-7, MDA-MB-231, and MDA-231BO2, and the osteolytic prostate cancer cell line PC-3 were analyzed for RANK expression by RT-qPCR (Fig. 1a). The gene discussed is TNFSF11; the disease is breast cancer.