Important in this context, neoplastic glial cells with astrocytic morphology also express GFAP.[39] Within the tumor microenvironment, reactive astrocytes activate JAK/STAT signaling—often via interleukin‐6 secretion—triggering the expression of vascular endothelial growth factor (VEGF) and thereby promoting angiogenesis and the formation of MVPs. The gene discussed is VEGFA; the disease is neoplasm.