Src activity is required for α6β4 dependent VEGF translation. Whole cell lysates were prepared from MDA-MB-231 cells and MDA-MB-435/β4 cells treated with DMSO or 10 μM PP2 overnight (A) and infected with GFP or c-Src shRNA (B). The relative VEGF mRNA content of each sucrose gradient fraction was measured by Real time PCR and normalized to GFP mRNA (external control) as described in the Methods. The data are represented as the mean ratio of VEGF to β- actin mRNA (± SD) obtained from triplicate samples. The statistical analysis was done using Student’s t-test. * P < 0.05, **P < 0.01. U, untranslated complexes (fractions #1-3); L, light polyribosomes (fractions #4-8); H, heavy polyribosomes (fractions #9-12).