Glioblastoma is an aggressive form of brain cancer with little therapeutic options available and of particular interest in disease progression is the activation of specific proteins via phosphorylation by protein kinases. Trialling of new therapies therefore may wish to profile these pathways. The Xevo™ MRT MS with <1ppm mass accuracy coupled with the selectivity of multiple reaction monitoring (ToF-MRM) and the standardised and reproducible chromatography provided by the Evosep system, allows for accurate and quantitative characterization of PTMs surrounding the identified peptide markers.