GU81-alone but not in combination with doxorubicin induces macrophage infiltration in vivo. Tumor sections from each group were evaluated for macrophage infiltration by assessment of F4/80+ cells (A&B) using immunohisochemistry. Representative images from saline and GU81 treated animals are displayed in (A). (B) The percent F4/80 positive area was calculated using Elements software and is displayed as the mean +/- SEM. All quantification includes 3 animals/group and 5 sections/animal. * p < 0.05 vs control, t-test. (C) Linear regression analysis reveals a positive correlation between VEGF levels and macrophage infiltration following therapy. r2 = 0.89.