KDR and myocardial ischemia: By contrast, Ho et al [42] report that knocking out VEGFR1 in postnatal and adult mice increased angiogenesis after cardiac ischemia, which increased the bioavailability of VEGF-A for binding to VEGFR2, markedly increased the expression of VEGFR-2 protein, and promoted signaling downstream of VEGFR2.