Basement membrane may participate in vascular remodeling in response to sustained VEGF blockade. Using immunohistochemistry for the perivascular basement membrane component collagen IV and Masson's trichome stain for total collagen, it was found that the perivascular basement membrane formed a thin sleeve around vasculature in untreated tumors. After 15 days of treatment with VEGF Trap, it increased significantly, forming a thick layer encasing vasculature, confirmed as significant by image analysis. Thus, tumor vascular recovery appeared concurrent with a striking and quantitatively highly significant increase in vascular basement membrane. For details, see the article by Kadenhe-Chiweshe and colleagues 1.