TYR and melanoma: In fact, 4SCP was found to be as good a substrate for melanoma tyrosinase as L-tyrosine [16] and a good inhibitor of L-tyrosine transport to melanoma cells, implying the efficient transportation of 4SCP [61], and 3H-4SCP was specifically incorporated into cultured human melanoma cells in vitro [62] and mouse melanoma tissues in vivo [16].