VEGFA and neoplasm: Both VEGF and its receptor are expressed at high levels in metastatic human colon carcinomas and in tumor associated endothelial cells, and production of these two proteins correlates directly with the degree of tumor vascularization.[11–13] A prevalent hypothesis is that the cells that make up the new lining of blood vessels which respond to the tumor cytokines, belong to the primitive blasts of both hematopoietic and endothelial origin (EPCs).