Effect of downstream intron on NMD of the R1032Gfs*25 mutation. (A) Diagram of the minigenes of WT, R1032Gfs*25 and R1032Gfs*25 without intron 14. (B) RPA analysis of mRNA from WT, R1032Gfs*25 and R1032Gfs*25 without intron 14 minigenes. Cells were treated (+) or not treated (−) with 100 μg/ml of CHX for three hours before RNA isolation. RPA signals were quantified, normalized to hygromycin resistance gene (Hygro), and shown as percentage of WT control (n=3 or 4, **P<0.01).