CSF1R and rheumatoid arthritis: To extend our knowledge about the role of CSF1R signaling in RA, we used blocking antibodies to CSF-1 (clone 26730), to IL-34 (M2), or to CSF1R (huMab1) to investigate the differential effects of inhibiting responses to each ligand independently versus inhibiting responses to both ligands simultaneously through CSF1R blockade.