In addition, we show that activity of bone resorption is compromised in osteoclasts lacking ELMO1, and Elmo1 knockout mice exhibit alleviated bone erosion in a serum transfer induced rheumatoid arthritis model, suggesting that ELMO/DOCK/RAC axis regulates RANKL-stimulated osteoclast differentiation and bone resorption activity, both in vitro and in vivo. Here, ELMO1 is linked to rheumatoid arthritis.