PDGFRB and rheumatoid arthritis: Bielen et al. found that phosphorylation of platelet-derived growth factor receptor (PDGFR) α/β suppresses autophagy by activating the PI3K/Akt/mTOR signaling pathway, thereby preventing RA-FLS from undergoing type II apoptosis induced by excessive autophagy and leading to continuing proliferation of RA-FLS and aggravation of the pathogenetic condition [30].