GPX4 and rheumatoid arthritis: found that ferroptosis decreased in the RA synovium and FLSs, with the decreased level of ACSL4 and the increased levels of FTH1, GPX4, and SLC7A11, and glycine enhanced ferroptosis via S-adenosylmethionine (SAM)-mediated GPX4 promoter methylation and FTH1 decrease (41).