E8431 is a DCSTAMP antagonist, where DCSTAMP is a crucial fusion protein that coordinates cell-cell fusion during osteoclastogenesis. E8431 inhibits cytoskeletal reorganization mediated by the RAP1B-RAC1 signaling pathway. It has the ability to prevent pre-osteoclast fusion, suppress bone resorption, and stimulate PDGFBB secretion, thereby promoting bone and vessel formation. E8431 effectively reduces bone loss in mouse models induced by ovariectomy. This compound can be used for osteoporosis research.