KDR and neoplasm: Both VEGFR2-targeting and pHSV-TK contributed to improving the anti-tumor efficiency: 25 days after tumor implantation, the tumor volume was 9.7 ± 5.2 mm3 for the pHSV-TK/GCV-loaded VEGFR2-targeted microbubbles-treated group, 40.1 ± 4.3 mm3 for the untargeted pHSV-TK/GCV-loaded microbubbles-treated group, and approximately 68 ± 8 mm3 for the untreated group [104].