It was previously shown that GH action in GHR+ human melanoma cells upregulates while GHR knockdown suppresses the ABC-transporter system, especially ABCB1, ABCB5, ABCB8, ABCC1, ABCC2, ABCG1, and ABCG2 differentially in a drug-dependent manner [21]. This evidence concerns the gene ABCG2 and melanoma.