Objective    To screen an endothelial cell line with calcium/calmodulin-dependent serine protein kinase (CASK) knockdown and explore the cells’ reaction to hypoxia stress.     Methods    CASK RNA interference plasmid pGenesil-siCASK and control plasmid pGenesil-Negative were generated

and then transfected into EA.hy926 endothelial cells with liposome followed by screened with G418. The expression of CASK was detected in normal

pGenesilsiCASK and pGenesil-Negative transfected cells with Western blotting. Hypoxic stress was induced in the transfected and untransfected cells cultured under an atmosphere with an airflow (94%N

2

5%CO

2

and 1%O

2

) at 10 L/min in an interval of 5 min inflow and 5 min stillness for 3 times. After the cells were cultured for 0

1

3

6 and 12 h

the cell cycle was investigated by using flow cytometric analysis.     Results    Western blotting results showed that CASK was mildly expressed in the EA.hy926 cells after pGenesil-siCASK transfection

while its expression had no obvious change in those transfected with pGenesil-negative. The cell proliferation indexes of EA.hy926 cells were elevated by short term hypoxia (0 h: 42.93%

1 h: 50.46% and 3 h: 52.53%)

while were decreased with the prolongation of hypoxic duration (6 h: 40.71%

12 h: 25.18%). However

the proliferation indexes of CASK-knockdown endothelial cells were not changed significantly under transient hypoxic stress.     Conclusion    CASK knockdown endothelial cells have less proliferation changes than EA.hy926 endothelial cells under short term hypoxic stress.