KDR and neoplasm: In fact, very few studies have reported sorafenib inhibition of VEGFR phosphorylation in either implanted tumor models or in cancer patients in vivo, and even in those cases where inhibition was reported, the observed decreases in phospho-VEGF were partial, were not localized to tumor blood vessels, and mirrored the general decreases in tumor blood vessel density that result from sorafenib treatment [50-52].