SLC9A1 and lung cancer: Supporting this hypothesis, TXNIP mRNA expression is inversely correlated with three critical regulators of proton export that function to increase intracellular pH (Webb et al., 2011): monocarboxylate transporter (MCT) 1 in lung cancer, MCT4 in breast cancer and sodium-hydrogen antiporter 1 (NHE1) in brain cancer (Figure 1—figure supplement 1A).