ROCK inhibition of MC3T3-E1 cells reversed this low cell activity on the HPB surface. Cells treated with Y-27632 on the HPB surface were round in shape (Fig. 2A). The inhibition of ROCK by Y-27632 increased cell adhesion and proliferation (Fig. 2B and C). The portion of cells in the S/G2/M phases was increased by treatment with Y-27632 on the HPB surface (Fig. 3A). Since entry into the S phase in the
Bazedoxifene requires the accumulation of cell cycle activation-related cyclins and the down-regulation of cyclin-dependent kinase (CDK) inhibitors [21] and [22], we assessed the expression levels of cyclins and CDK inhibitors such as p21cip1 (p21) and p27kip1 (p27) to determine whether the increased cell proliferation on the HPB surfaces by ROCK inhibition involved these proteins. There was a lower expression of cyclin D1 and a higher expression of p21 and p27 in MC3T3-E1
cells on the HPB surface compared to the cells on the HPL surface (Fig. 3B). Treating cells with Y-27632 up-regulated cyclin D1 and down-regulated p21 and p27 on the HPB surface. These results suggest that the down-regulation of CDK inhibitors such as p21 and p27 is related to the increase in cell proliferation on the HPB surface upon ROCK inhibition by Y-27632.
