Actinomycin D suppressed the upregulation of TRPM1 mRNA, which is transcriptionally activated upon treatment of melanoma cells with BRAF inhibitor (Supplementary Fig.3a)37 but did not affect HIF1A mRNA (Supplementary Fig. 3b), confirming that the dose of actinomycin used was sufficient to block transcription completely. Here, TRPM1 is linked to melanoma.