Figures 3(a) and 3(b) show the meta-analysis of associations of only PDGFR expression and only PDGF expression on the one hand and PDGF/PDGFR system expression in RA patients examined in Asian countries and Western countries on the other hand in Figures 3(c) and 3(d). This evidence concerns the gene PDGFRB and rheumatoid arthritis.