The HMB45 clone reacts with a neuraminidase-sensitive oligosaccharide side chain of a glycoconjugate present in immature melanosomes. The HMB45-reactive antigen is present in cutaneous melanocytes, prenatal and infantile retinal pigment epithelium and melanoma cells. It is also thought to be oncofetal in nature. This antibody has been shown to label the majority of melanomas. The MART-1/Melan A recognizes a protein of 18kDa, identified at MART-1 (Melanoma Antigen Recognized by T cells 1) or Melan-A. The MART-1 recognizes a subcellular fraction found in melanosomes. The antibody labels melanomas and tumors showing melanocytic differentiation (1,2). It does not mark neoplasms of epithelial origin, lymphomas or mesenchymal tumors. Melan-A is a useful addition to melanoma panels which are specific to melanocytic lesions. Studies have also shown that MART-1 is more sensitive than HMB45 when labeling metastatic melanomas. HMB45 and MART-1 are coexpressed in the majority of melanomas, as well as solely expressed in certain cases. Thus, the HMB45 and MART-1 cocktail is potentially more sensitive than HMB45 and MART-1 alone. The MART-1 is a cocktail of clones M2-7C10 + M2- 9E3. The combination of HMB45 and the MART-1 cocktail make this triple antibody cocktail a first-order pan melanoma screener (3).