IL21 and rheumatoid arthritis: Expression of PD-1, CXCL13, IL21, TIGIT, PRDM1, TOX, CD39, TIM3, CTLA-4, CXCR3, CCR2, HLA-DR, and CXCR6 is commonly shared with the signature of TPH CD4 cells in the synovium of RA patients, and of TRM-like CD4 T cells like neoantigen-reactive CD4 T cells in metastatic human cancers, tumor-infiltrating CD4 T cells, liver-infiltrating CD4 T cells in HBV-infected and HCC patients, and liver-resident CD4 T cells23,30,39–41,44,56–58,61–65.