Human Glioblastoma (HGB) cell lines, obtained from primary cultures of six patients with histo-pathologically diagnosed Glioblastoma, each demonstrated glial fibrillary acidic protein (GFAP) and IGF-1 positivities by indirect immuno-cytochemical staining technique using mouse anti-human IGF-1 monoclonal antibody. Here, GFAP is linked to glioblastoma.