ANGPT1 and neoplasm: To further elucidate the effect of the deletion of TGF-β signaling deletion in tumor ECs, we directly assessed the secretion of established angiogenic factors in these tumor-bearing mice using a mouse angiogenesis antibody array (Figure S3) in conjunction with subsequent real-time quantitative PCR (qPCR), which revealed elevated relative expressions of proangiogenic factors, including VEGF-A and angiopoietin 1, in the TβRIIiΔEC mice when compared with those in the control mice (Figure 3C).