For example, TNF promotes osteoclast differentiation by promoting RANK and T cell nuclear factor (NFATc1) expression in osteoclast precursor cells.[98] TNF also promotes M‐CSF expression by bone marrow stromal cells to stimulate osteoclast formation.[99] In addition, TNF also acts directly on osteoclast precursor cells and promotes their differentiation into osteoclasts.[100] Besides, other cytokines also cause bone erosion in RA. This evidence concerns the gene CSF1 and rheumatoid arthritis.