TNFSF11 and rheumatoid arthritis: RANKL was abundantly expressed in the joint cavity of RA patients and combined with RANK on the surface of osteoclasts and osteoclast precursor cells, inducing the proliferation and differentiation of osteoclast precursor cells, increasing the activity of osteoclasts, and promoting bone resorption, as well as inhibiting the differentiation and function of osteoblasts.