Figure 2.

AUDE-containing mRNAs are stable in 5637 bladder carcinoma cells and in NIH 3T3 cells treated with the calcium ionophore A23187. RNA was isolated at various times after serum stimulation of cells stably transfected with chimeric fGH genes containing either a synthetic A+U-destabilizing sequence (fGH-AU1) or the A+U-rich region from G-CSF (fGH-AU2), inserted in the 3′UTR. Specific mRNAs were quantitated by an RNase protection assay. Both mRNAs were unstable in NIH 3T3 cells but stable in 5637 cells, and both were stabilized in NIH 3T3 cells treated with A23187. The graphs show data as mean ± SEM from three experiments. RNase protection gels from a single representative fGH-AU2 experiment are shown, with an arrow indicating the fGH-AU2 signal and the signal from the glyceraldehyde-3-phosphate dehydrogenase internal standard indicated by a G.