Comparison of the FACS assay with RT-PCR/MLPA. (A) RT-MLPA analysis of p53 target genes 16 hours after irradiation. P21, BAX, and PUMA were induced in samples with wild-type p53. Samples with the 17p deletion showed a reduced induction. NOXA, on the contrary, was not induced. (B) P21, BAX, and PUMA measured by RT-MLPA versus p53 basal levels determined by FACS. All genes identified the 17p-deleted cases and 2 of the samples with the TP53 mutation. The use of p21 induction measured by RT-MLPA seemed to provide the best separation among the 3 genes. (C) Analysis of miR-34a in 55 samples of the original cohort in untreated cells and 16 hours after 5-Gy irradiation. 17p-deleted samples could be detected by miR-34a expression at baseline and after 5-Gy irradiation and its absolute induction. (D) miR-34a analysis in 36 samples of the validation cohort in untreated cells and 24 hours after irradiation (5 Gy).