TYR and melanoma: The above results are also similar to those observed in melanoma, whereby amelanotic tumour samples remain positive for Mitf (King et al, 1999).The apparent absence of tyrosinase in our experiments is consistent with earlier studies of most CCS cell lines (Epstein et al, 1984; Sonobe et al, 1993; Liao et al, 1996; Hiraga et al, 1997), which are only weakly melanotic.