KDR and neoplasm: It should be noted that co-delivery of two different drugs targeting ECs (e.g. VEGFR inhibitor) and PC/SMCs (e.g. PDGFRβ inhibitor) was more effective in inhibiting tumor development than individual anti-angiogenic drugs, presumably because they enhanced the destabilization of vessels by inhibiting PC/SMC function, thus rendering ECs more susceptible to EC blockers [93–94].