Splicing correction in COS-1 cells. (A-B) COS-1 cells were transfected with the mutant or wild-type F5 minigene construct and either left untreated or treated with the indicated concentrations of rescuer MO or control MO. (C-D) COS-1 cells were transfected with the mutant or wild-type F5 minigene construct and either left untreated or cotransfected with the indicated amounts of the U7-SmOPT construct expressing anti-F5 (rescuer) U7snRNA or control 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. Representative gels are shown. M, 100-bp marker; Untr., untreated; R-MO, rescuer MO; C-MO, control MO; R-U7, rescuer U7snRNA; C-U7, control U7snRNA.