A humanized, immunoglobulin G1 monoclonal antibody with potential antitumor activity. MORab-003 specifically targets at glycoprotein 3 (GP-3), a cell surface antigen that is overexpressed on many epithelial-derived cancer cells. Upon binding to the GP-3 antigen, MORab-003 triggers a host immune response against GP-3 expressing cells resulting in cell lysis.