Figure 10. Effect of collagen aging on ERK1/2 activation and p21^CIP1 expression.

A. ERK1/2 western blot analysis of HT-1080 cells after 5 days culture in adult and old type I collagen 3D matrices. The histograms show the ratio of pERK1/2 expression relative to total ERK1/2. B. Effect of ERK1/2 inhibitor U0126 on cell proliferation. HT-1080 cells were seeded in adult and old type I collagen 3D matrices at a density of 1.5 × 10⁴ cells/ml, with or without 5 μM U0126. After 5 days of culture, cell density was evaluated by phase contrast microscopy. C. p21^CIP1 western blot analysis of HT-1080 cells after 5 days culture in adult and old type I collagen 3D matrices. The histograms show the ratio of p21^CIP1 expression relative to GAPDH. D. Effect of U0126 on pERK1/2 and p21^CIP1 expression. HT-1080 cells were seeded in adult and old type I collagen 3D matrices at a density of 1.5 × 10⁴ cells/ml, with or without 5 μM U0126. After 5 days of culture, western blot analysis was performed using pERK1/2 and p21^CIP1 specific antibodies. Values represent the mean ± S.E.M. of three independent experiments (*p < 0.05, ***p < 0.001).