Figure 3.

Effects of exogenous IGFBP-2 on invasive potential of glioblastoma cells and ERK activation. (A and B) Exogenous IGFBP-2 significantly enhanced invasion by glioblastoma cells in a dose-dependent manner, as determined using the Matrigel assay. A U87 cells were presented as examples. (upper) left: control; right: 125 ng ml⁻¹ IGFBP-2. (Lower) left: 250 ng ml⁻¹ IGFBP-2; right: 500 ng ml⁻¹ IGFBP-2. (B) Effects of exogenous IGFBP-2 on the invasive potential of various glioblastoma cells. (C and D) Exogenous IGFBP-2 enhances ERK activation in glioblastoma cells. (C) A 30-min treatment with 500 ng ml⁻¹ IGFBP-2 induced an increase in phospho-ERK expression levels, whereas total ERK protein levels were not significantly altered, as assessed by western blot analysis. (D) Extracellular signal-regulated kinase (ERK) phosphorylation and nuclear translocation resulting from a 30-min treatment with 500 ng ml⁻¹ IGFBP-2, as visualised by immunofluorescence staining. The mean values from triplicate samples of three independent experiments are shown. *P<0.05 and **P<0.01.