Figure 2: Influence of collagen density on spreading, cytoarchitecture and focal adhesions in MDA-MB-231 cells. (A) Representative phase contrast images of MDA-MB-231 cells cultured on collagen -coated coverslips at different densities for 24 hours. Scale bar=50 μm. (B) Projected cell area on coverslips coated with collagen at varying densities. Pluronic-blocked coverslips (Plu.) without any matrix coating served as negative controls. Cell spreading increased with increasing ECM density. Bars indicate statistical significance (*p < 0.05). (C) F-actin (red) and vinculin (green) distribution in cells cultured on collagen-coated surfaces at varying densities. Merged images show the co-localization of the actin fibers and vinculin at the points of focal adhesion formation (yellow). Prominent stress fibers were observed across all the conditions. Scale bar=20 μm. (D) Average size of focal adhesions increased with increasing collagen density. Bars indicate statistical significance (*p < 0.001).