Analysis of mRNA expression for β2-M and CDKIs by real-time RT-PCR. (A) Dose-dependent amplification of β2-M mRNA by real-time RT-PCR. Top panel: The intensities of fluorescence signal of the FAM dye (delta Rn) are plotted on the y-axis and the cycle number is plotted on the x-axis. The amplification plots shifted to the right as RNA levels were reduced (from 100 ng to 10 pg, 1:10 diluted). The threshold cycle (C_T) is defined as the cycle number at which the delta Rn of a sample crossed a threshold of 10 SD above baseline fluorescence. Bottom panel: The C_T value is plotted on the y-axis and the amount of RNA input is plotted on the x-axis. The C_T value decreases linearly with the RNA input. (B) Time-dependent induction of mRNA for CDKIs by TBI. Mice were exposed to 6.5 Gy TBI or unirradiated as control. At 1, 3, 7, 14, 28, and 56 days after TBI, BM-MNCs were isolated from irradiated and unirradiated mice and then RNA was extracted from these cells and analyzed by real-time RT-PCR to determine mRNA expression for various CDKIs. A representative analysis of CDKI mRNA expression by real-time RT-PCR is presented as mean ± SD of triplicate (ΔΔC_T-CDKI = ΔC_T-IR - ΔC_T-CTL; ΔC_T-IR = C_T-IR/CDKI - C_T-IR/β2-M; ΔC_T-CTL = C_T-CTL/CDKI - C_T-CTL/β2-M).