KDR and neoplasm: Wu and Nyborg (2008) found that the inertial cavitation caused by microbubbles not only destroyed tumor microvessels but also resulted in direct tumor cell damage. Moreover, Zhang et al. (2014) suggested that the downregulation of vascular endothelial growth factor receptor-2 and αvβ3 integrin expression was partly responsible for the suppression of tumor growth with ultrasound treatment.