Figure 5.

ARRB1 knockdown induced G₂/M phase arrest and down-regulation of cyclin B1, CDC25C, and CDK1 in glioblastoma cells. U251 and U87 cells expressing shRNA against ARRB1 (sh-1 and sh-2) or sh-c were treated with hHK-1. A, FACS analysis of the cell cycle. ctl, control. B, the proportions of cells in G₂/M phase are presented as mean ± S.E. from three independent experiments. ***, p < 0.001 versus sh-c. Synchronized cells were harvested to analyze protein expression. C, Western blot analysis of cyclin B1 (anti-cyclin B1, 1:1000), pCDK1(Tyr¹⁵) (anti-pCDK1(Tyr¹⁵), 1:1000), and pCDC25C(Ser²⁶¹) (anti-pCDC25C(Ser²¹⁶), 1:1000). Total Akt served as a control. D, densitometry of cyclinB1, pCDC25C(Ser²¹⁶), and pCDK1(Tyr¹⁵) levels was calculated by Quantity One software (corrected with GAPDH). The results are means ± S.E. for three independent experiments.