Fig. 1.

Prominent expression of AKT signaling pathway components. Representative immunohistochemical localization of low and high expression of p-AKT within the nuclei of tumor cells from patients with meningioma (A) and medulloblastoma (B) respectively (magnification 100×). Also note, membranous immunolocalization of p-S6 kinase was present within the cells in all 18 tumor samples (representative samples from 2 patients with ependymoma are shown here, C and D). Variability of staining was noted within the tumor and demonstrated that more than half of cells within the tumor had at least moderate intensity of staining. Thus, the AKT signaling pathway appears to be broadly expressed and is presumably active in several types of relapsed pediatric brain tumors.