c-met expression is up-regulated during the earlier steps of angiogenesis in vitro. (A) c-met and VE-cadherin immunostaining patterns in HUVECs cultured in a 3-dimensional collagen gel for 0, 4, 8, and 24 hours. At the indicated times, the cells were recovered from the parallel collagen cultures, and processed for Western blot analysis. Images in far left column are phase micrographs. For all images in panel A: original magnification, × 400. Blots probed with anti–c-met (B) or with anti–VE-cadherin antibodies (C) are shown, along with the corresponding scanning densitometry results. In panels B-C, relative density is reported in arbitrary units. (D) Filters were stripped and reprobed with an antiactin antibody. Data are representative of 5 independent experiments.