PDGFB and neoplasm: The pro-tumorigenic role of Pax3 in glioma is brainstem-specific, as co-injection into the cortex of both PDGF-B and Pax3 did not significantly reduce survival or increase tumor penetrance (p = 1.0) or grade (p = 1.0) compared to injection of PDGF-B alone (Additional file 8: Figure S4).