IL6 and rheumatoid arthritis: Interestingly, another study showed that long-standing RA-derived FLS constitutively expressed basic fibroblast growth factor (FGF), TGFß, IL-1α, and IL-6 but not TNFα (12), suggesting that FLS are constitutively prone to synthesize IL1-α and ß and mostly IL-6, IL-8, and TGFß but not TNFα.