Related to Figs. 3–5. a, The GSH to GSSG ratios in melanoma cells from mice treated with AZD3965 or DMSO (two independent experiments per melanoma). b, Quantitative analysis of NADPH and NADP+ in melanoma cells from mice treated with AZD3965 or DMSO (one or two experiments per melanoma). Liver cells were included as a control, with a high NADPH/NADP+ ratio. c, Expected isotope-labelled species after infusion of [1,2-13C]glucose. d, Glucose m + 2 as a fraction of total plasma glucose in mice xenografted with efficiently metastasizing melanomas (M405, M481 and UT10), treated with DMSO or AZD3965 and infused with [1,2-13C]glucose. e, Glucose m + 6 as a fraction of total plasma glucose in mice infused with [U-13C]glucose. The number of mice per treatment is indicated (two independent experiments). f–i, LC–MS measurement of the levels of glycolytic (f, h) and oxidative PPP (g, i) metabolites in subcutaneous tumour cells from mice xenografted with melanomas treated with DMSO (control) or AZD3965 (MCT1 inhibitor) for 7 days. j, Flow cytometrically isolated MCT1high or MCT1−/low melanoma cells were subcutaneously transplanted into NSG mice, using 10 or 100 cells per injection. All injections formed tumours. Rate of growth of the tumours initiated with 10-cell injections. Data are mean ± s.d. Statistical significance was assessed using t-tests (a), repeated-measures two-way ANOVAs (b), t-test (e, 180 min), log2-transformed two-way ANOVAs (f, h), log2-transformed t-tests (g, M405 and UT10), Mann–Whitney test (g, M481 and i, M481), Welch’s t-tests (i, M405 and UT10) or using nparLD test (d, j).