PECAM1 and neoplasm: To this aim, we used formalin-fixed paraffin-embedded (FFPE) murine 4T1 tumors and simultaneously evaluated CD8 (cytotoxic T cell marker), CD31 (blood vessels marker, for tracking the CD8 infiltration pattern), and pan-cytokeratin (pan-CK)/E-cadherin (tumor markers)26 (N = 12 images from 3 mice per group were analyzed).