Figure 2.

Effect of DDR1 silencing on the growth response of MCF-7 and ZR-75-1 cells in adult and old type I collagen 3D matrices. A. DDR1 and DDR2 expression was analyzed by immunoblotting. HT-1080 cells were used as a positive control for DDR2. GAPDH was used as a loading control. B. MCF-7 (left panel) and ZR-75-1 (right panel) cells were transfected with control or DDR1 siRNA. DDR1 expression was analyzed B. 24 hours and C. 6 days after transfection by immunoblotting. GAPDH was used as a loading control. D. DDR1-silenced cells were embedded in adult or old 3D collagen matrices at a density of 1.5 × 10⁴ cells/ml. After 6 days of culture, viable cell density was assessed by phase contrast microscopy. E. MCF-7 cells were transfected with control or DDR1 siRNA. After 36 hours, DDR1 and DDR2 expression was analyzed by immunoblotting. HT-1080 cells were used as a positive control for DDR2. Data are representative of three independent experiments. Values represent the mean ± S.E.M. of three independent experiments (**p < 0.01, ***p < 0.001, N.S = not significant).