TYR and melanoma: In G361, human melanoma cells stimulated with the cyclic adenosine monophosphate (cAMP) elevator, 3-isobutyl-1-methylxanthine (IBMX), the relative mRNA levels of MITF, TYR, TRP-1, and DCT were significantly increased to 1.94 ± 0.19, 2.70 ± 0.15, 1.50 ± 0.18, and 1.60 ± 0.31, respectively, compared to those of the untreated cells.