<prompt> DENOSUMAB a monoclonal antibody against RANKL receptor is used in the treatment of ?Rheumtoid ahritisOsteoporosisOsteoahritisSLE  <response>: Ans. is b i.e., Osteoporosis Donesumab o Osteoclast is a cell responsible for bone resorption. o Osteoclasts express RANK receptors on its surface RANK -- receptor activator for nuclear factor. o When RANK receptor combine with their ligands RANKL osteoclastogenesis is initiated and bone resorption occurs. o Donesumab is a monoclonal antibody against RANK ligand. o It prevents the activation of the osteoclasts by these ligand. Note : o Osteoporosis is a disease characterized by decrease in the bone mass. o In osteoporosis there is increase in the osteoclast activity and there is increased expression of RANK and RANKL. 