SLC2A4 and cancer: Although not much is known concerning the involvement of GLUT4 in cancer biology (51–53), downregulation of GLUT4 expression in the breast cancer cell lines MCF-7 and MDA-MB-231 cells impaired basal glucose uptake, promoted metabolic reprogramming from lactate production to oxidative phosphorylation and decreased cell proliferation and viability, strongly suggesting the participation of this transporter in basal glucose uptake in breast cancer cell lines with different degrees of malignancy and differentiation (54).