THYMIDYLATE SYNTHASE antibody has been tested for use in ELISA, immunoprecipitation, immunofluorescence microscopy, immunohistochemistry and immunoblotting. The antibody recognizes the expected additional band corresponding to the ternary complex of hTS-dFUMP-reduced folate in HeLa cells treated with the TS inhibitor 5-FUdR. This event occurs in most human breast, colorectal, gastric, head and neck carcinomas. The antibody recognizes the 36,000 MW hTS. Reactivity in other immunoassays is unknown.