NKI/C-3 recognizes a melanoma-associated antigen present in the cytoplasm of melanoma cells and nevocellular nevi, in contrast to most mabs against melanoma-associated antigens present in the membrane, which are not retained after formalin fixation. Therefore, the mab is very useful for paraffin sections in routine pathology. Cross reactivity with carcinoids, medullary carcinomas of the thyroid, and occasionally prostatic, primary breast, avarian, and lung carcinomas may be observed. No reaction is seen with basal cell carcinomas or brain tumors. NKI/C-3 does not react with normal melanocytes or other normal tissues except for mastcells, histiocytes, salivary glands, bronchial glands, pancreatic und prostatic epithelium. For the diagnosis of melanoma, the antibody should be used in combination with other antibodies (e.g. cytokeratin immunoreactivity indicative for carcinoma versus vimentin immunoreactivity indicative for melanoma). In immunoblotting the antibody reacts with diffuse protein bands between 25 and 100 kD.Positive control: Melanoma.