PDGFRA and glioblastoma: U87 GBM cells were treated with 1 μM CP-673451 for 0, 15 min, 1, 4, 24 and 48 h (Supplementary Fig. 2A, B) and phosphorylated levels of PDGF-Rα/β and PDGF-Rβ were measured by western blotting.