RNA degradation negatively affects PCR signals irrespective of mRNA amplicon size. RNA from PBL blasts was degraded by exposure to 90°C. PCR signals for high-abundance (green), medium-abundance (red), and low-abundance (blue) mRNA transcripts were assessed. For each transcript, size of the amplicon was varied (50 bp, 100 bp, 200 bp, or 400 bp). For each condition, the mean PCR signal at t=0 was set to 1. Graph represents means of 4 experiments, with third-order polynomial lines drawn through the data points. *P < .05; #P < .01; **P < .001 vs mean of first two time points for the smallest amplicon.