Induction of CDKN1A (□), MDM2 (◊), and GADD45A (○) in ML-1 cells by 50 cGy X-rays delivered at 0.28 cGy/min. Induction of CDKN1A (□), MDM2 (◊), and GADD45A (○) in ML-1 cells by 50 cGy X-rays delivered at 0.28 cGy/min. Time is measured from the end of the irradiation period. Dashed line, level of gene expression in the un-irradiated control culture. A similar temporal pattern of gene induction was observed in TK6 cells (data not shown). Sally A. Amundson et al. Mol Cancer Res 2003;1:445-452 ©2003 by American Association for Cancer Research