The expression of ephrinB2 and EphB4 proteins in pyogenic granuloma and cell cultures. (A) A representative double staining from specimens of pyogenic granuloma, which is a hyperreactive inflammatory lesion. EphB4 was detected with peroxidase-AEC (3-amino-9-ethylcarbazole) and appeared red (red arrow). Positive staining for ephrinB2 was dark blue, which was detected by alkaline phosphatase–NBT/BCIP (nitroblue tetrazolium/5-bromo-4-chloro-3-indoyl phosphate p-toluidine salt). Most of the ephrinB2-positive cells were macrophage-like cells (white arrowhead), while EphB4-positive cells were in small venules. Original magnification × 400. Scale bar equals 20 μm. (B) Western blots for ephrinB2 and EphB4 in 5 human primary cell cultures, including 4 endothelial cells (HUAECs, HUVECs, HIAECs, HSVECs) and 1 fibroblast (human gingival fibroblast [HGF]), and 1 monoblastoid cell line (U937) activated with 20 ng/mL PMA. [Beta]-Actin was an internal control.