Abstract: The present invention is directed to novel methods of treating or diagnosing a hyperproliferative disease or disorder in an patient, where the methods include administrating to the patient a binding molecule which binds to a cell surface-expressed glycoprotein expressed predominantly in tumor or tumor-associated cells. In particular, the therapeutic and diagnostic methods of the present invention include the use of a binding molecule, for example an antibody or immunospecific fragment thereof, which specifically binds to the human LRRC15 protein. The present invention further provides a method of isolating and identifying cell surface expressed glycoproteins expressed in tumor or tumor associated tissues, where the method includes isolating desired glycoproteins via their affinity for specific lectins.