MMP13 and rheumatoid arthritis: Consistent with this, other studies have shown that RA FLS proliferation is mediated by IGF-IR/PI3K/AKT m-TOR signalling pathway [146], that knockdown of Raptor (a component of mTORC1) reduces IL-1β-induced MMP3 and MMP13 expression in human intervertebral discs [147], and that mTORC1 blockade reduces synovial osteoclast formation, thus protecting the joint from bone erosion [148].