CSF1 and rheumatoid arthritis: Cells derived from PB and SF of patients with RA were stimulated with M-CSF alone (M-CSF), a combination of M-CSF and sRANKL (MCSF + sRANKL), or a combination of M-CSF, sRANKL, and rIL-9 (M-CSF + sRANKL + rIL-9) for 4 days.