Glucose transporter 1, also known as GLUT-1 antibody or SLC2A1 is a protein in humans encoded by the SLC2A1 gene. GLUT-1 antibody facilitates the transport of glucose across the plasma membranes of mammalian cells. GLUT1 is responsible for the low-level of basal glucose uptake required to sustain respiration in all cells. Several glucose transporter protein isoforms have been identified and shown to function in response to insulin and IGF-1 induced signaling. Immunohistochemical studies have shown GLUT-1 expression in many human tissues including those of the colon, lung, stomach, esophagus and breast. A high expression of GLUT-1 immunoreactivity in cancer has been associated with aggressive behavior and shorter disease-free survival. Hypoxia in cancer has a significant impact on clinical outcome and surrogate markers for tumor hypoxia, such as GLUT-1 and HIF-1 alpha, have shown prognostic significance for patient outcome. Recently, studies have also shown that GLUT-1 was positive in most mesotheliomas, but was negative for reactive mesothelium.