Nuclear-cytoplasmic distribution of luc -mRNA. Nuclear and cytoplasmic fractions were obtained from NIH3T3 cells transfected with R7f-L and Rec5-L and RNA was extracted from each fraction. The amount of spliced luc-mRNA and gapdh-mRNA in each fraction was quantified by real-time RT-PCR. The mean values from 3 independent experiments and the SEM are shown. Statistical comparison was done using the t test.