Osteoprotegerin (OPG), which acts as a sink for RANKL, was significantly elevated in BALF after HPD treatment compared to LPD or RD treatment (Fig. 7f) of Npt2b−/− mice, providing a plausible explanation for the decrease in RANKL-dependent osteoclast gene expression and TRAP positive MNGC formation that were found in the lungs of the HPD mice (Fig. 7a, b). The gene discussed is TNFSF11; the disease is disseminated peritoneal leiomyomatosis.