1. Proteomics Unit; Spanish National Cancer Research Center; Madrid Spain
2. Gastrointestinal Cancer Clinical Research Unit; Clinical Research Program, Spanish National Cancer Research Center; Madrid Spain
3. Molecular Pathology Programme; Spanish National Cancer Research Center; Madrid Spain
4. Departament de Ciències Experimentals i de la Salut; Universitat Pompeu Fabra; Barcelona Spain
5. AB Sciex; Edificio Sotohenar; Madrid Spain
6. Centro Integral Oncólogico ‘‘Clara Campal’’; Hospital Universitario Madrid Sanchinarro; Madrid Spain