IRDye® 800CW EGF Optical Probe is a BrightSite™ near-infrared (NIR) fluorescently-labeled recombinant human epidermal growth factor (EGF). Epidermal growth factor receptor (EGFR) is one of a family of receptor tyrosine kinases found on the surface of epithelial cells, to which EGF binds. Many types of cancer cells have abnormally high EGFR levels on the cell surface. In vivo assays of EGF binding have proven effective in monitoring specific solid tumor models that exhibit overexpression of EGFR. EGF conjugated to the LI-COR NIR fluorophore, IRDye 800CW provides a versatile probes that can be used for in vitro and in vivo assays, as well as whole organ and tissue section analysis.