FN1 and neoplasm: The discovery of a prominent presence of untensed Fibronectin fibers in invasive tumors, which increases with tumor progression, and their proximity to cancer cell nests, α−SMA positive CAFs, and particularly immune cells is of paramount importance, as the physical signature of individual ECM fibers might play so far unrecognized roles in tumor progression, as well as immune cell silencing or sequestration.