Fig. 3.

EphB4^OE tumors revealed sustained functioning vessel networks following antiangiogenic treatment in the chronic cranial window. a Sample pictures of IVM in the chronic cranial window on the respective postoperative days, demonstrating also increased diameter in resistant tumor vessels and in EphB4 overexpression glioma vessels; EphB4 overexpression vessels do not respond to sunitinib treatment. Scale bars as indicated. b–e Evaluation of TVD and FVD: a significant reduction of TVD (**p < 0.01, ***p < 0.001; all groups n = 5) and FVD (*p < 0.5, **p < 0.01; all groups n = 5) in treated control tumors on day 14 and 16 p.o. All values are presented as mean ± SD. f–h Vessel enlarging effect observed in therapy-resistant control vessels as well as in EphB4^OE-vessels (*p < 0.05, **p < 0.001, ****p < 0.0001; all groups n = 5); EphB4 overexpressing glioma vessels do not respond with further vascular enlargement to sunitinib treatment while demonstrating resistance towards antiangiogenic treatment. All values are displayed as mean ± SD