Genomic amplification of the MITF locus, which may occur in 10–15% of metastatic melanomas [23], was unlikely to underlie the differential expression of MITF between our Motif 1 and 2 NZM cell lines as there was no difference in MITF copy number between NZM cell lines with varying levels of relative MITF gene expression (Figure S3). The gene discussed is MITF; the disease is melanoma.