Figure 8. p27/Kip1 mediates the arrest of cell proliferation and cell cycle progression. (A) Detection of p27 protein by western blotting following shRNA knockdown. Cells transduced with p27 shRNAs or a control shRNA for 3 d were collected and examined for the expression of p27 protein. (B) Knockdown of p27 abolished the arrest of cell proliferation imposed by contact inhibition in the mutant cells. Cells transduced with p27 shRNAs or a control shRNA for 48 h were reseeded at 2 × 104 cells/well in 6-well plates and counted daily. (C) Knockdown of p27 abolished the arrest of cell cycle progression imposed by contact inhibition in the mutant cells. Cells transduced with p27 shRNAs or a control shRNA for 48 h were reseeded at high-density at 106 cells/flask in T25 flasks for 48 h and analyzed for cell cycle.