SLC2A1 and astrocytoma (excluding glioblastoma): The astrocytoma/glioblastoma U87 cell line, which expresses very low levels of GLUT-1 due to a transdominant negative mutation in one of the alleles of GLUT1 (GLUT-1 D5), is easily infected by HTLV-pseudotyped viruses[3,56].