CD44 and neoplasm: These results suggest that VEGF secreted from GSCs not only has an angiogenic effect on the endothelial cells of tumor vessels in a paracrine manner through VEGFR2 on endothelial cells, but also negatively regulates expression of CD44 and c‐Met in an autocrine manner through VEGFR2 on the tumor cells, thus, resulting in suppression of tumor invasion and migration when the tumor is proliferating due to the angiogenic activity of VEGF.