Transfection with human CCL2 has been reported to suppress the in vivo growth and tumorigenicity of CHO cells (Rollins and Sunday, 1991) and melanoma cells (Bottazzi et al, 1992), and the fusion of tumorigenic HeLa cells, which do not express CCL2, with normal fibroblasts, resulted in CCL2 expressing somatic hybrids unable to form tumours in nude mice (Rosl et al, 1994). This evidence concerns the gene CCL2 and melanoma.