An integrated comparative phosphoproteomic and bioinformatic approach reveals a novel class of MPM-2 motifs upregulated in EGFRvIII-expressing glioblastoma cells

Mol Biosyst. 2009 Jan;5(1):59-67. doi: 10.1039/b815075c. Epub 2008 Oct 30.


Glioblastoma (GBM, WHO grade IV) is an aggressively proliferative and invasive brain tumor that carries a poor clinical prognosis with a median survival of 9 to 12 months. In a prior phosphoproteomic study performed in the U87MG glioblastoma cell line, we identified tyrosine phosphorylation events that are regulated as a result of titrating EGFRvIII, a constitutively active mutant of the epidermal growth factor receptor (EGFR) associated with poor prognosis in GBM patients. In the present study, we have used the phosphoserine/phosphothreonine-specific antibody MPM-2 (mitotic protein monoclonal #2) to quantify serine/threonine phosphorylation events in the same cell lines. By employing a bioinformatic tool to identify amino acid sequence motifs regulated in response to increasing oncogene levels, a set of previously undescribed MPM-2 epitope sequence motifs orthogonal to the canonical "pS/pT-P" motif was identified. These motifs contain acidic amino acids in combinations of the -5, -2, +1, +3, and +5 positions relative to the phosphorylated amino acid. Phosphopeptides containing these motifs are upregulated in cells expressing EGFRvIII, raising the possibility of a general role for a previously unrecognized acidophilic kinase (e.g. casein kinase II (CK2)) in cell proliferation downstream of EGFR signaling.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Motifs
  • Antibodies / immunology*
  • Antibody Specificity
  • Antigens / chemistry
  • Antigens / immunology
  • Cell Line, Tumor
  • Computational Biology
  • ErbB Receptors / metabolism*
  • Glioblastoma / immunology*
  • Glioblastoma / metabolism*
  • Humans
  • Phosphoproteins / analysis*
  • Phosphoproteins / chemistry
  • Phosphoproteins / immunology*
  • Phosphoproteins / metabolism
  • Up-Regulation*


  • Antibodies
  • Antigens
  • Phosphoproteins
  • epidermal growth factor receptor VIII
  • ErbB Receptors