IRS1 and glioblastoma: Researchers measured miRNA expressions in different tumor cell lines and found that compared to normal brain tissue, miR-7 was down-regulated in astrocytoma and neuroblastoma, Research on a glioblastoma cell line demonstrated that miR-7 could repress EGFR expression and also downregulate IRS-1 and IRS-2 expression by suppressing the activity of protein kinase B (PKB; Liu et al., 2014).