The aim of this study was to establish whether the expression of proto-oncogene c-ski in melanoma might be related to alterations of chromosome 1q involving the native location of the gene. Six melanoma cell lines, including two carrying marker chromosomes derived from breakage at 1q12-q21, were studied. Expression of c-ski was observed in all cell lines, with very high levels in five of them. However no alteration in c-ski structure or dosage was found in any of the melanoma cell lines, including those with non-random breakpoints near the gene. c-ski Transcripts were detected in cell cultures from normal melanocytes, but at a much lower level than that observed in melanoma cell lines. Transcripts of c-myb and the beta-NGF gene were not detectable in any of the melanoma cell lines, whereas sis- and epidermal growth factor (EGF) receptor gene-specific transcripts were present in two and four melanoma cell lines, respectively. The constant expression of c-ski in the melanoma-derived cell lines at a level of expression much higher than that of normal melanocytes suggests that this proto-oncogene may play a role in melanocyte transformation.