Additionally, experimental studies with lung cancer cells have found that they secrete parathyroid hormone-related protein (PTHrP), which binds to the PTH/PTHrP receptor, enhances the expression of the receptor activator of nuclear factor-kappa B ligand (RANKL), and inhibits the synthesis of osteoprotegerin (OPG) (30). The gene discussed is PTHLH; the disease is lung carcinoma.