The attributes of pPDGFRαβ+CDH11– cells accumulating in the RA-SL were clarified by comparing the expression levels of TNF-R1, Bcl-2, p16, and p53 between pPDGFRαβ+CDH11–, pPDGFRαβ-CDH11+, and pPDGFRαβ+CDH11+ cells in the RA-SL (Figure 2A). This evidence concerns the gene BCL2 and rheumatoid arthritis.