In this regard, we measured galectin-3, MPO, matrix metalloproteinase 9 (MMP-9), hepatocyte growth factor (HGF) and interleukin 8 (IL-8) in sera of 50 advanced melanoma patients (stage IV) receiving MAPK inhibitors as first-line therapy, and evaluated their relevance as predictive serum biomarkers comparing responders (PR) and nonresponders (PD). The gene discussed is MPO; the disease is melanoma.