CA9 and neoplasm: The observed higher expression of LDH-A has been previously found in less aggressive 67NR breast cancer cells under hypoxia in preclinical model16 and more differentiated tumours in patients with gastric cancer,32 while observed higher LDH-B in higher grade is in agreement with previous studies in breast cancer.33 However, carbonic anhydrase IX (CA9), a strong prognostic marker, has been recently shown to induce an acidic tumour extracellular pH in vivo,34 decoupling lactate production regulated by LDH and lactate concentration.