Antibodies to intracellular domains of two or more kinds of protein tyrosine phosphatases, methods for generation thereof and cells producing these antibodies are disclosed. The antibody of the present invention may have specificity to intracellular domains of phosphatase subunits of both of LAR and CD45, and may be useful for analysis and quantitative determination of PTPs, identification and detection of novel PTPs, and for obtaining novel phosphatases by cloning and the like, as well as for developing useful diagnostic methods of insulin resistance and NIDDM, for prophylaxis and diagnosis of various disease states of syndrome X that is based on insulin resistance, and for prophylaxis and diagnosis of onsets of arteriosclerosis and cardiac diseases.