['8-Chloro-adenosine(8-Cl-Ado) is an anti-tumor drug,which has been investigated and developed recently in China. The molecular mechanism of 8-Cl-Ado is now unclear. This study was conducted to investigate the effect of 8-Cl-Ado on the activity of transcription factor cAMP-response-element-binding protein(CREB) and its correlative mechanism in human promyelocytic leukemia cell line HL-60.', 'MTT method was used to determine IC(50) (the concentration showing 50% of inhibition rate) of 8-Cl-Ado to HL-60. The protein levels and phosphorylated levels of CREB at different time following 8-Cl-Ado stimulation were examined using Western blot analysis. Gel shift assay was performed to examine DNA binding levels of CREB at different time following 8-Cl-Ado stimulation.', '(1)The IC(50) of 8-Cl-Ado to HL-60 was about 0.42 micromol/L. (2)8-Cl-Ado increased phosphorylated level of CREB rapidly, which was maximal at 30 minutes, and returned to basal level in 6 hours. The protein level of CREB was constant during 8-Cl-Ado stimulation. (3)8-Cl-Ado did not influence binding level of DNA and CREB.'] Does [ 8-Chloro-adenosine increase the activity of transcription factor CREB by modification of phosphorylation ]?