IL6 and rheumatoid arthritis: Thus, we conducted quantitative reverse transcription‒PCR (qRT‒PCR) and enzyme-linked immunosorbent assay experiments, which revealed that PLCη2_C2 overexpression reduced the expression and secretion of several proinflammatory cytokines (for example, IL-6) and Matrix Metalloproteinases (MMPs) in RA FLSs (Fig. 2e, f).