Parathyroid hormone-related protein (PTHrP), produced by cancer cells, enhances receptor activator of nuclear factor kappa B ligand (RANKL) expression and inhibits osteoprotegerin (OPG) secretion from osteoblasts and stromal cells, thus activating osteoclastogenesis via RANK located on osteoclast precursors [14]. This evidence concerns the gene PTHLH and cancer.