The epithelium-to-stroma MCT4 ratio demonstrated very strong positive correlations with lactate SNR and combined epithelial LDH expression (rs = 0.90 and 0.93, P = 0.002 and 0.001; Fig. 2b, Supplementary Table 3), thereby suggesting an association between [1-13C]lactate labelling, tumour LDH activity, and compartmentalised MCT4 expression. This evidence concerns the gene SLC16A3 and neoplasm.