Comparison of Flt-1 and VWF promoter activity in tumor xenografts.

Uniform and strong LacZ staining was detected in Lewis lung carcinoma (A) and B16-F1 melanoma (B) xenografts from Flt-1-lacZ-Hprt mice. In contrast, there was no detectable reporter gene activity in Lewis lung carcinoma (C) and B16-F1 melanoma (D) xenografts from VWF-lacZ-Hprt mice. Arrowheads indicate the X-Gal reaction product in capillaries of adjacent skeletal muscle. Broken lines indicate the border between tumor layer and adjacent skeletal muscle layer. Photographs were taken at × 100 optical magnification. The results are representative of at least 2 independent experiments.