Taken together with our previous work which showed strong positive associations between tumour [1-13C]lactate SNR, total epithelial LDH density, and epithelial LDHA/PDHA1 ratio2, these results indicate that tumour [1-13C]lactate labelling is likely to be a function of both the epithelial capacity for cytosolic LDH-catalysed pyruvate reduction, and MPC-driven mitochondrial pyruvate import. The gene discussed is PDHA1; the disease is neoplasm.