TGM2 and rheumatoid arthritis: In the current study, we took advantage of the promising applications of a coumarin‐derived active ingredient OS that exhibited anti‐RA effects by regulating proliferation, migration, and invasion of RA‐FLS via downregulating TGM2‐mediated signaling and presented anti‐RA‐ILD effects via attenuating the proliferation and polarization of CD11b+ M2 macrophage.