SLC2A1 and neoplasm: Accordingly, we found that hypoxia tended to increase GLUT1 and GLUT4 expressions in A-549, A-427 and MCF-7 tumor cells and MCR-5 fibroblast cells; but only A-427 cells presented significant differences, and MCF-7 did not increase GLUT4 under hypoxia (Figures 4B,C).