KDR and pilocytic astrocytoma: We assessed expression of KIT, phosphorylated KIT, stem cell factor (SCF) and vascular endothelial growth factor receptor‐2 (VEGFR‐2) in 35 juvenile pilocytic astrocytomas and 49 other pediatric brain tumors using immunohistochemistry, and KIT messenger RNA (mRNA) using in situ hybridization.