Expression of hybrid Th17 cell phenotypes is associated with diseases like rheumatoid arthritis or colon cancer, which involve IL‐17+Foxp3+Treg cells or RORγt/Foxp3+Treg cells, respectively (57, 72), a pattern generated by modeling under lack of glutamine and IL-4, combined with moderate levels of IL-6 and IL-21, as shown in line 7 of Table 1. Here, IL21 is linked to rheumatoid arthritis.