Figure 1. Postnatal deletion of Tgfbr2 in endothelium delays tumor growth and impairs blood vessel formation.

(A) Study design including tamoxifen treatment and orthotopic mammary tumor injection schedule for control versus Tgfbr2^iECKO mice. (B) Mammary tumors from control mice versus those from Tgfbr2^iECKO mice. Tumor volumes were determined with calipers using the formula: volume = (length × width²)/2. Final tumor weights are presented in grams (control, n = 12; Tgfbr2^iECKO, n = 15). *P < 0.05, by ANOVA with Sidak’s multiple comparisons test (volume) and Student’s t test (weight). (C) CD31 staining of control versus Tgfbr2^iECKO mammary tumors. The inset images show a representative open or closed lumen of a blood vessel in each tumor. Scale bars: 100 μm; zoom, ×4 (insets). (D) Percentage of vascular area and number of open lumens per field in tumors from control versus Tgfbr2^iECKO mice (n = 5 tumors examined per group). *P < 0.05, by Student’s t test. (E) Image analysis scheme to determine branch lengths in tumors from control versus Tgfbr2^iECKO mice. See Methods for analysis details. The representative vessel is from the far-right inset in C. Scale bar: 100 μm. (F) Quantification of branch lengths in control versus Tgfbr2^iECKO tumors using the “analyze skeleton” feature in ImageJ Fiji (see Methods for details). Results were determined by Mann-Whitney U test. Histogram analysis of branch length shows the number of branches binned per 20-pixel interval (n = 3 tumors per group). Data represent the mean ± SEM.