Splicing correction in HepG2 cells. HepG2 cells were transfected with the mutant F5 minigene construct and either left untreated or treated with 5 μM rescuer MO or cotransfected with 2 μg of the U7-SmOPT construct expressing anti-F5 (rescuer) U7snRNA. The 2-μg U7-SmOPT construct corresponds to a molar excess of 4.8× over the F5 minigene construct. After 48 hours RNA was isolated, reverse-transcribed and analyzed by PCR and gel electrophoresis (A) and real-time qPCR (B). The gel shows the effects of 5 μM R-MO and 2 μg of rescuer U7snRNA construct on F5 pre-mRNA splicing in HepG2 cells transfected with the mutant F5 minigene (quadruplicate transfections). Results of the quantification experiments are expressed as the ratio between the aberrant and normal F5 mRNA, plotted on a logarithmic scale. The quantification data represent the mean ± SD of the 4 replicates. M, 100-bp marker; Untr., untreated; R-MO, rescuer MO; R-U7, rescuer U7snRNA.