EphrinB phosphorylation marks angiogenic vessels. (A) ROP model: P7 mice were exposed to 75% oxygen tension for 5 days (P12) and then to normal oxygen tension for 1 day (P13), 3 days (P15), and 5 days (P17). Representative confocal images from retinal whole mounts show vascular p-EphrinB in p15 and p17. HypoxyProbe marks hypoxic areas. P13 original magnification ×10 p13 and ×20 p15 and p17. (B) p-EphrinB and actin in retinal extracts from p6, adult, and ROP (P13, P15, and P17) mice detected by immunoblotting. (C) Skin wound-healing model. Representative H&E staining (left) of a 2-day-old wound showing the disrupted epithelium; CD31 and p-EphrinB immunostaining of boxed area (expanded on the right). The epithelium displays intense nonspecific green fluorescence seen from secondary-only antibody. (D) Selected capillaries from control and wounded skin detected by confocal microscopy after immunostaining. (E) MOPC315 tumor model. Tumor vessels (CD31⁺) show variable pericyte (NG2⁺) coverage and p-EphrinB expression. The boxed area (expanded bottom right) shows vascular localization of p-EphrinB immunostaining. Scale bars in panels A and D represent 20 μm. Original magnification in panels C and E is ×20.