MPO and neoplasm: Immunostaining for myeloperoxidase (MPO) showed that both tumor cells and neutrophils (which are mostly in the peri-tumoral region) stained for MPO, making the analysis of neutrophilic recruitment problematic (Figure 6A, third row), however semi-quantitative scoring focusing on the peri-tumoral regions, did not reveal any significant difference among the treatment groups (Figure 6C).