EGFR and glioblastoma: We demonstrate that Crk Tyr221 and Tyr251 are routinely and iteratively tyrosine phosphorylated by EGF in EGFR-expressing glioblastoma cell lines (GBM), and at both the biochemical and cell biological level, the level of Tyr251 Crk phosphorylation strongly correlates with Abl kinase activation, as well as the invasive properties of GBM cells.