IFNG and rheumatoid arthritis: IFN‐γ secreted by metastases‐infiltrating lymphocytes leads to tumor evasion by upregulating negative immune checkpoints molecules, such as PD‐L1, which is an important mechanism in the immune escape of tumor cells.[41] IFN‐γ also reportedly enhances the immunosuppressive function of MSCs[42] and is a key factor in determining the efficacy of MSCs in RA treatment.[43] In addition to PD‐L1, inhibitory molecules including Gal‐9,[44] FasL,[45] and CD47[46] are reportedly upregulated by IFN‐γ.