This is supported by expression of the hypoxia-induced glucose transporter, GLUT-1, and carbonic anhydrase isoform 9, CA-IX, adjacent to necrotic zones in DCIS as well as the upregulation of GLUT-1 and sodium hydrogen exchanger (NHE-1, a marker for extracellular acidosis) in regions of microinvasion [26]. Here, SLC2A1 is linked to ductal breast carcinoma in situ.