PDGFA and glioma: Based on the concurrent expression of PDGFA and PDGFRA in glioblastomas, it could be hypothesised that autocrine/paracrine loops may be present in these tumours, corroborating the importance of this signalling pathway in gliomas (Nister et al, 1991; Guha et al, 1995; Fomchenko and Holland, 2007).