Immunohistochemical analysis of biopsies, cytology specimens or surgical resection specimens using antibodies directed towards tumor-associated antigens, lineage or differentiation antigens is a technique often used by surgical pathologists to aid in establishing the correct histologic classification of malignant tumors. With the proliferation of experimental approaches to cancer treatment using monoclonal antibodies as targeting agents, it is anticipated that surgical pathologists will increasingly be receiving requests from clinicians to define the antigen profile in biopsy specimens, even when not necessary to render the correct tumor classification. Clinicians may use the immunohistochemically delineated antigen profiles provided by surgical pathologists to plan tailored treatment regimens utilizing monoclonal antibodies to the antigens expressed in the tumor biopsy to target anticancer therapeutic agents. Some of the potential problems in such a process might include the differing sensitivities, and perhaps specificities, of the antibodies used for analyzing the surgical pathology biopsy specimens compared to the monoclonal antibodies actually used {\it in vivo}. Our approach to this dilemma is to develop murine monoclonal antibodies to tumor-associated antigens that can reliably be used to detect antigens in routinely processed surgical pathology specimens as a starting point for further therapeutic monoclonal antibody development.