Fig. 2.

SP-A eB enhances transcription in the natural and heterologous 5′UTR sequence context. Luciferase mRNA expression (expressed as firefly-to-Renilla ratio, relative to LUC control), measured by real-time RT-PCR after 30 h of transfection of NCI-H441 cells with experimental constructs containing eB upstream of the SP-B and SP-D 5′UTRs, or within the SP-A 5′UTR sequence. The sequence of eB was also placed upstream exons A and D (eBAD), or inverted (inveBAD). The presence of eB in the natural or heterologous 5′UTRs resulted in higher transcription, even when eB was inverted (*P < 0.05, vs. constructs without eB). This effect was not observed when eB was replaced by a random sequence of the same length (ran). The control construct without 5′UTR (LUC) exhibited the lowest mRNA levels (#P < 0.001 vs. all constructs). Real-time RT-PCR was done in triplicate for each sample. Each bar shows mean + SE (n = 3–6 independent experiments).