Effect of p56/Lck on angiogenesis in vivo. Matrigel plugs were prepared in wild-type mice as described in Materials and Methods. Angiogenesis in plugs was quantified 9 d after placement by immunofluorescence staining and determination of hemoglobin content. A–F) Representative fields are shown from Matrigel plugs containing growth factors (bFGF and VEGF) and heparin (A) heparin alone (B), growth factors plus heparin plus empty lentivirus (used as control) (C), growth factors plus heparin plus lenti-p56/Lck (D), growth factors plus heparin plus HKa (E), and growth factors plus heparin plus HKa plus lentivirus expressing p56/Lck shRNA (F). G) Hemoglobin content of plugs, prepared as described. GF, growth factor; LV, lentivirus; WT, wild type. Data represent mean ± sem of 10 plugs derived from 5 mice each receiving 2 plugs. Scale bars = 100 µM.