YTHDF2 and rheumatoid arthritis: As shown in Figure 1(a)–1(f), compared with normal controls, the expression of METTL3 was significantly increased in PBMCs from RA patients, while no difference was observed with regard to other key m6A methylation-related enzymes (METTL14, FTO, ALKBH5, YTHDF1, and YTHDF2).