To determine whether CD148 was present in synovial joints in human rheumatoid arthritis patients, immunofluorescence was performed with CD148 and CD68 (as a marker for macrophages); CD11c (as a marker for dendritic cells); CD3 (as a marker for T cells and/or thymocytes); CD90 (as a marker for stromal fibroblasts and endothelium); and von Willebrand factor (vWF) (as a marker for endothelial cells/blood vessels). This evidence concerns the gene PTPRJ and rheumatoid arthritis.