SYK and rheumatoid arthritis: Otherwise, Mun and co-workers reported that TNF-α-induced interleukin-32, which is a recently discovered proinflamatory cytokine that appears to play a critical role in human rheumatoid arthritis (RA), is positively regulated via the Syk/protein kinase Cδ/JNK pathway in rheumatoid synovial fibroblasts [41].