EPHB4 and neoplasm: With regard to functional tumor vasculature, assessed by intravenous (i.v.)injection of the fluorescence dye Hoechst 33,342 (H33342) and subsequent fluorescence microscopy of tumor sections, only in the NVPiso group did we observe the already known effect, that A375-pIRES tumors are more vascularized than A375-EphB4 tumors (Figure 3a).