Figure 3

(a) Relationship of HIF-1α expression in OA and RA with VEGF/KDR vascular activation pathway. Note that the degree of VEGF/KDR microvessel density is directly correlated with the degree of HIF-1α expression only in the case of OA; VEGF/KDR is consistently high in RA, and higher than in OA. (b) Relationship of HIF-1α expression in osteoarthritis (OA) and rheumatoid arthritis (RA) with stromal cell thymidine phosphorylase (TP; referred to in the text as platelet-derived endothelial cell growth factor [PD-ECGF]) reactivity. Note that the degree of TP expression is directly correlated with the degree of HIF-1α expression only in the case of OA; TP expression is consistently high in RA, and higher than in OA.