Figure 6. Caffeine enhanced the heat cytotoxicity of rad9, rad17 or atm DT40 cells.

A–C. Clonogenic survival. atm (A), rad9 (B) and rad17 (C) DT40 cells were cultured at 45°C for the indicated time in the presence or absence of 2 mM caffeine. D–F. Apoptosis. atm (D), rad9 (E) and rad17 (F) DT40 cells were cultured at 45°C for 60 minutes and at 39.5°C for 60 minutes in the presence or absence of 2 mM caffeine. (D) *p = 0.0012, (E) *p = 0.0057, (F) *p = 0.0084 (Student's t test).