To gather further evidence that promotion of cTregs’ conversion into IL-17+ T cells contributes to the observed enhancement of DSS-induced SKG arthritis by Ptpn2 haploinsufficiency, we bred Ptpn2fl/+ SKG mice with a tamoxifen-inducible Treg fate-mapping model (44). This evidence concerns the gene PTPN2 and arthritic joint disease.