Accordingly, we divided Tregs into ‘naïve’ CD45 RA+ cells and memory CD45 RA–cells, the latter which were also subdivided into central memory CD45 RA–CCR7+ Tregs, effector memory CD45 RA–CCR7– Tregs (that were thought to be tissue-infiltrating Treg subsets), and CD45 RA+ CCR7– terminally differentiated Tregs [43,44]. The gene discussed is PTPRC; the disease is rheumatoid arthritis.