PDGFRB and glioblastoma: However, the extent to which ABL signalling influences GBM cell biology still remains elusive as: a) ABL and PDGFR reciprocally regulate their phosphorylation levels in GBM cells [47]; b) the beneficial effects of Imatinib cannot be attributed to one single target, since it simultaneously inhibits PDGFR and ABL (in addition to KIT) [45, 50].