SLC2A1, also known as GLUT1, is an ubiquitously expressed glucose transporter and responsible for the basal level of glucose uptake in most cell types. Human erythrocytes express the highest level of the SLC2A1. Defects in SLC2A1 are the cause of GLUT1 deficiency syndrome type 1 and type 2. High expression of SLC2A1 has been reported to be a reliable immunohistochemical marker for juvenile hemangiomas. GLUT1 protein may appear as two or more distinct forms among 43 kDa to 55 kDa due to the different glycosylation state.