ABC, subfamily B, member 5 (ABCB5)29 and ABC, subfamily G, member 2 (ABCG2)30 are members of this superfamily of proteins, and are known molecular determinants of cancer stem/initiating cells of melanoma.29, 30 We investigated if FKBP51 modulated MCSC phenotype. The gene discussed is ABCG2; the disease is cancer.