EPHB4 and neoplasm: Another mAb (C2), targeting the cysteine-rich domain of EphB4, also inhibited the tube-forming behavior of MDA-MB-231 breast tumor cells in vitro (indicative of vasculogenic behavior), and tumor growth of xenografts; however xenografts of PC3 prostate cells were unaffected, thought to be due to their low cell surface receptor expression [55].