The invention provides methods for detecting and inhibiting angiogenesis, endothelial cell adhesion, and endothelial cell migration using agents which inhibit the specific binding of integrin α4β1 to one or more of its ligands. The invention further provides methods for screening test compounds for their ability to inhibit angiogenesis, endothelial cell adhesion, or endothelial cell migration by employing agents which inhibit the specific binding of integrin α4β1 to one or more of its ligands. The invention additionally relates to methods for isolating endothelial progenitor cells which express integrin α4β1. The methods of the invention are useful in, for example, diagnosing and inhibiting pathological conditions that are associated with angiogenesis, endothelial cell adhesion, and/or endothelial cell migration. The invention's methods are also useful in isolating endothelial progenitor cells, and in determining the mechanisms that underlie angiogenesis, development, wound healing, and the function of the female reproductive system.