IGFBP2 and glioblastoma: Serum IGFBP-2 levels and tumor IGFBP-2 expression are dramatically elevated in a variety of human malignancies including GBM [14], [21], [22], and it has been reported that preoperative plasma IGFBP-2 levels are correlated with recurrence and disease-free survival in patients with GBM [8].