CTSK and melanoma: Further analysis of these factors, however, reveals that while both of these subclasses are MITF-associated, the degree of association is higher for subclass C. Examining downstream targets of MITF that are activated in each subclass (see Supplementary Note 12), we identified that GPNMB, MLANA, PMEL, and TYR are shared between two subclasses, whereas ACP5, CDK2, CTSK, DCT, KIT, OCA2, and TRPM1/P1 are unique to subclass C. To validate these targets, we used a comprehensive list of downregulated genes in response to MITF knockdown in 501Mel melanoma cells21.