Using 3D collagen-FN matrices, we first quantified T-cell speed and overall motility using the persistent random walk model (PRWM), for both primary human CD4+ (hCD4+) T cells that were available from healthy human donors (see “Methods”) and mouse CD8+ (mCD8+) T cells where cytotoxic T cells from tumor-bearing hosts could be obtained from genetically engineered KPC mice bearing pancreatic tumors, which are highly faithful to the human disease4,15,62. Here, CD4 is linked to neoplasm.