As discussed previously, increased bone resorption releases bone matrix-derived growth factors such as TGF-β, IGFs and FGFs, all of which can stimulate tumor cell growth and/or increase PTHrP production, defining a vicious cycle of osteolysis (Chirgwin and Guise, 2000; Mundy, 2002; Kremer et al., 2011). Here, PTHLH is linked to neoplasm.