Our global gene analysis showed that the melanoma initiating cells marker ABCB5 is downregulated in both SLM8 and Mela1 spheroids compared to their adherent counterparts, although we did not detect ABCB5 at the protein level nor find side-population cells described to be associated with ABCB5 expression [59] in either population. The gene discussed is ABCB5; the disease is melanoma.