Influence of extracellular matrix (ECM) protein and fibroblast composition in cancer cell migration. (a) Schematic of the experimental process consisting of cell seeding, media exchanges, and imaging after 48 h of culture to track cell migration. (b,c) Fluorescence images of green fluorescent protein (GFP) tagged MDA-MB-231s within different matrix compositions in co-culture with human mammary (HMFs) and cancer-associated fibroblasts (CAFs). (b) MDA-MB-231 co-cultures with HMFs in a collagen matrix (left) and a fibronectin-rich matrix (right). (c) MDA-MB-231 co-cultures with HMFs in a collagen matrix (left) and a fibronectin-rich matrix (right). Scale bar = 200 µm. (d) The average number of cells in the matrix. (e) Average migration distance measured from the edge of the lumen after 48 h of culture. (f) Representative western blot of fibronectin (g) Quantification of fibronectin protein normalized to total protein determined by SYPRO Ruby staining (whole lane fluorescence). Bars represent average ± SD, n = at least four individual devices. * p ≤ 0.05, ** p ≤ 0.01.