NFATC1 and rheumatoid arthritis: Real-time PCR analysis revealed that rIL-9 stimulation along with M-CSF and sRANKL significantly enhanced the expression of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), a master transcription regulator of osteoclast differentiation in cells derived from PB of HC, PB, and SF of patients with RA (Figure 1B).