For this, we investigated two different human breast carcinoma cell lines (MDA-MB-231 and MCF-7 cells), two different mouse embryonic fibroblast cell lines (PINCH-1 knock-out (PINCH-1−/−) cells and controls (PINCH-1fl/fl), as well as 3D collagen gels with and without fibronectin crosslinking. The gene discussed is FN1; the disease is breast carcinoma.