Osteoprotegerin(OPG) ,receptoractivatorofNF -κBligand (RANKL)andreceptoracti vatorofNF -κΒ(RANK)areimportantmoleculesthatregulateosteoclastogenesis .OPGisdecoyreceptorof RANKL .ThebindingofOPGandRANKLblocksconnectingofRANKLandRANK ,inhibitsdevelopmentof osteoclast.ThebindingofRANKLandRANKinducesaserieskinasecascadereaction ,activatestranscription factors,introducestheproliferationanddifferentiationofosteoclastprecursors .Severalhormonesandos teotropicfactorsregulatetheformationandfunctionofosteoclastthroughtheabovemolecules .