Validation of microarray selected genes by quantitative real-time RT-PCR; confirmation of validated genes on 22 B-CLL samples. Expression patterns of 16 selected genes by microarray analyses specifically regulated in the resistant B-CLL subset were verified by RT-PCR on 22 B-CLL samples: 7 samples included in microarray analyses, 7 new sensitive, 4 resistant expressing p53wt as well as 4 new resistant samples expressing p53mt. Microarray data on the expression levels of 14 genes were validated by RT-PCR and all but one gene were confirmed on all included B-CLL cell samples. The names of genes are indicated in red or green characters according to their up- or down-regulation. Data are expressed as means of duplicate experiments for each of 22 samples. The median + SD, median + SE, median, median – SE and median – SD are shown. (A) Relative constitutive expression levels (in absence of irradiation) in sensitive (S) and resistant (R) subset revealed 3 up-regulated transcripts (TR3 orphan receptor, HLA-DQA, and mtmr6), and 4 down-regulated transcripts (stat1, blk, MIP1α, and hsp27). (B) Relative expression levels before and after 3 hours of irradiation in sensitive (S and S′, respectively) and resistant (R and R′, respectively) samples revealed 4 up-regulated (mat2A, c-myc-P64, c-rel, and c-myc ORF114), and 2 down-regulated transcripts (ech1 and hypothetical protein [hp] A4); only ech1 was confirmed in all resistant samples. (C) RT-PCR ratios in resistant samples expressing p53mt before (Rmt) and after irradiation (R′mt) and p53wt (R and R′) pointed out c-IAP1 as the more efficiently up-regulated transcript following irradiation in resistant samples expressing p53wt. Following irradiation, APR peptide appeared as up-regulated in p53mt-expressing samples and down-regulated in resistant samples expressing p53wt. Note that this transcript was neither validated nor confirmed as modified in resistant samples according to p53 mutation status. Fibromodulin (fmod, X75546) was validated as being induced by irradiation in resistant samples expressing p53mt (R′mt) as compared to sensitive (S′) and resistant (R′) samples, both expressing p53wt.