Decay of reporter mRNAs. SiHa cells expressing the indicated constructs were treated with Actinomycin D to inhibit transcription. mRNA levels of the different GUS reporter mRNAs normalized to total RNA was determined with real-time RT-PCR at the indicated time points. At least three different measurements were made for each timepoint and the data plotted is the average relative to the mRNA level at the time of Actinomycin D addition. The error bars indicate the standard deviation.