Figure 6

Effect of Loratadine and Radiation on Cell Cycle Associated Proteins. In HT29 cells, activated pChk1^ser345 increases in response to loratadine (LR, 75 μM) within 6 hrs after exposure, peaks at 12 hrs and returns to baseline by 36 hrs. Total Chk1 decreases after exposure and remains depressed at 36 hrs. In irradiated cells, both pChk1^ser345 and Chk1 are increased at 8 and 16 hrs post-irradiation (8 Gy, 32 and 36 hr). Loratadine does not alter the radiation-induced increase in pChk1^ser345 at 8 hrs post-irradiation (8 Gy+LR, 32 hr) but abrogates the increase seen at 16 hrs (8 Gy+LR, 36 hr). Cyclin B1 increases in irradiated cells at 8 and 16 hrs post-irradiation (8 Gy, 32 and 36 hr) but in cells treated with loratadine (LR, 8 Gy+LR) Cyclin B expression falls below that seen in controls. The figure represents a single representative experiment.