The present invention provides methods and reagents for directing the selective targeting and entry of bacterial toxins to mammalian cells. Methods include the step of contacting a cell with a bacterial toxin or toxic bioactive fragment thereof associated with an antibody or ligand that is specific to a target on the cell, wherein the antibody or ligand selectively binds the target on the cell and the bacterial toxin or fragment thereof is internalized and enters the cell. The invention further encompasses compositions and kits to carry out the methods.
