Following our observation that RANKL/RANK control Brca1 mutation-driven tumorigenesis in mice and affect expansion of human BRCA1+/mut mammary progenitor cells, we analyzed RANK protein expression in human breast tumors that developed in BRCA1 or BRCA2 mutation carriers, and in non-BRCA1/2 mutated individuals. The gene discussed is TNFRSF11A; the disease is breast neoplasm.