Silencing of CDK11p110 induces apoptosis and cell cycle arrest at the G2/M phase in ESCC cell lines. (a) Apoptosis was determined by a flow cytometry analysis. EC109 and KYSE150 cells were transfected with siNC or siCDK11p110 for 72 hours. (b) Apoptosis rate of EC109 and KYSE150 cells after CDK11p110 knockdown. *P < 0.05, **P < 0.01, compared with siNC groups. NS, not significant. (c) The levels of the apoptosis-associated protein cleaved PARP were detected by western blot analysis in EC109 and KYSE150 cells after transfection with siNC or siCDK11p110 for 72 hours. (d) The alterations in cell cycle distribution of EC109 and KYSE150 cells were determined by flow cytometry after transfection with siNC or siCDK11p110 for 72 hours. (e) Ratios of cells in different cell cycle phases in EC109 and KYSE150 cells. Statistical analysis shows that the knockdown of CDK11p110 in EC109 and KYSE150 cells caused a significant G2/M arrest. **P < 0.01, ***P < 0.001 compared with siNC group. NS, not significant. All the data are presented as the mean ± SD (n = 3) and comparisons among three groups were analyzed by one-way ANOVA and comparisons between two groups were performed by student’s t test.