Nevertheless, under conditions of a highly active glycolytic metabolism with resultant accumulation of pyruvate and lactate (Warburg phenotype), induction of HIF-1α would be expected to occur in the GLUT-1 positive tumor areas according to the findings of Lu et al. [29], which should then, in turn, transactivate CA IX in the same tumor microregions, since CA IX is known to be one of the most robust and strongly induced target genes of HIF-1 [30, 31]. Here, CA9 is linked to neoplasm.