<p>Expression of vascular endothelial growth factor (VEGF) (dark brown colored) at different parts of the PTK787 treated and vehicle treated tumors. There were no differences observed in the expression of VEGF on immunohistochemistry at different parts of the tumors treated with either PTK787 or vehicle. However, delineation of vessels using FITC tagged tomato lectin indicated higher number of dilated vessels at the tumor periphery in rats that received PTK787 treatment. These dilated vessels may be indicative of increased permeability, fPV and signal intensity changes in PTK787 treated tumors (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008727#pone-0008727-g001" target="_blank"><b>Figures 1</b></a><b> and </b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008727#pone-0008727-g002" target="_blank"><b>2</b></a>). Increased permeability may also be due to increased VEGF expression. HIF-1α expression was mostly seen in the central part of the vehicle treated tumors (arrows), however, SDF-1 expressions were observed both in PTK787 and vehicle treated tumors (arrows).</p
