Fig. 1.

Endothelial Dll4 over-expression affects LLC subcutaneous xenograft growth and vasculature. a Dll4 over-expressed in endothelial cells retarded xenograft volume increase after subcutaneous LLC implantation in D4BE, D4BE + Doxy and D4OE littermates. Error bars represent SEM. *, P < 0.05 was considered significant. b Vascular response was examined in D4BE and D4OE tumor grafts using double immunostaining to endothelial PECAM and mural cell marker α-SMA. In relation with D4BE controls (above), the LLC xenografts developed in D4OE mice presented reduced vascular density (c), but increased vessel calibers (d) and promoted vessel wall assembly (e). Contrary to the D4BE tumor vessels that showed weak SMA staining and its co-localization with PECAM signals, SMA-positive cells lining PECAM-positive endothelium were distinctively increased in D4OE xenografts indicating improved vessel wall maturation. Dot lines mark tumor borders. Results are representative of n = 6 per mice group