Consistently to mRNA data, mass spectrometry data from GBM samples from Clinical Proteomic Tumor Analysis Consortium (CPTAC, see Materials and Methods) bearing either low- or high-grade increase of EGFR CN display a significant increase in CBX3 protein levels, and analogously, specimens with multiple copies of CBX3 gene show a statistically significant enrichment of EGFR protein levels (Fig. 4J, K). Here, CBX3 is linked to glioblastoma.