MTOR and rheumatoid arthritis: mTOR signaling controls the recruitment and activation of innate, acquired immune cells and fibroblast-like synoviocytes (FLSs) during RA, resulting in the production of numerous chemokines, pro-inflammatory cytokines, and cathepsin to degrade extracellular matrix and cartilage, further contributing to the early characteristics of synovitis [3, 54] (Fig. 3).