Using standard immunohistochemical technique to assess GFAP activity in tumor-bearing brain. (A) DBTRG glioma cells were introduced into mice by stereotactic injection. Following three weeks incubation, brains were harvested and sections were made to measure GFAP activity in tumor bearing vs. contralateral brain by immunohistochemistry. Sections were counterstained with DAPI and tumor area was defined by dense nuclei staining of the tumor cells (dotted line). An example of exposure-matched images of tumor-bearing brain (right) and its contralateral hemisphere (left) is shown. Note the upregulated GFAP activity at the tumor margin (right). Scale bar = 1 mm. (B) Fluorescently labeled DBTRG-Zsgreen glioma cells (green) were introduced into mice by stereotactic injection. Following three weeks incubation, brains were harvested and sections were made to measure GFAP activity (red) by immunohistochemistry. A representative image of upregulated GFAP immunoreactivity at the tumor margin compared to the tumor core is shown. Scale bar = 100 μm. (C) GFAP immunoreactivity in tumor margin (defined by fluorescent activity of the tumor cells), tumor core vs. normal area (contralateral) was quantified by measuring the fluorescent intensity of images in panel (B). Results are shown as an average of three mice. At least three independent areas were quantified from each mouse. P < 0.05, Wilcoxon rank sum test, two-sided. Error bar represents standard deviation.