GBM cell lines and tissues have been shown to express the IGF-1R.42,43 IGF-1R was seen to be overexpressed in GBM, and this overexpression was linked to shorter survival and reduced responsiveness to temozolomide, hinting at the role of IGF-1R signaling in GBM pathogenesis.44 This evidence concerns the gene IGF1R and glioblastoma.