TYR and melanoma: Tyrosinase is certainly a trigger of anti-melanoma effects of 4SCAP based on the results that (1) 2-S-cysteaminylphenol, an isomer of 4SCAP, did not act as a substrate of tyrosinase and did not exhibit any anti-melanoma and depigmenting effects [10], (2) the cytotoxicity of 4SCAP against various melanoma cell lines depended on the degree of their pigmentation [22], and (3) 4SCAP exhibited cytotoxicity to melanocytes in black mice but not in albino mice [23].