The Cultrex® In Vitro Angiogenesis Assay Endothelial Cell Invasion Kit was created in an effort to accelerate the screening process for compounds that influence vascular endothelial cell digestion of and invasion through a basement membrane extract (BME) layer. This kit offers a flexible, standardized, 96 well high-throughput format for quantifying endothelial invasion, in vitro, in response to chemoattractants and/or inhibiting compounds. This assay employs a simplified Boyden chamber-like design with an 8 micron polyethylene terephthalate (PET) membrane. Sulforaphane [1-isothiocyanato-(4R)-methylsulfinyl)-butane], a naturally occurring cancer chemopreventive agent, is provided as a control for inhibition of in vitro endothelial cell invasion through Cultrex® BME. Detection of cell invasion is quantified using Calcein-AM, which is internalized by the cells, and converted to the acetomethylester (AM) moiety by intracellular esterases. Free Calcein fluoresces brightly, and this fluorescence may be used to quantify the number of cells that have invaded using a fluorescence plate reader.