CHEK2 and breast cancer: By analyzing the induction of senescence in MCF-7 breast cancer cells induced by doxorubicin via ATM and chk2 activation, the authors stated that the sensitivity of the cells to this induced senescence could not be potentiated by a combination of a chk2 inhibitor, caffeine, and doxorubicin, nor by caffeine or the chk2 inhibitor alone.