Once breast cancer cells metastasize to the bone, they drive the osteoclasts toward matrix resorption, which enhances the ratio of RANKL/OPG in the osteoblasts, and directly produce soluble mediators capable of inducing osteoclast maturation, such as soluble RANKL (sRANKL) [17, 29]. The gene discussed is TNFSF11; the disease is breast carcinoma.