Fig. 8. PTCs can be recognized on a heterologous mRNA. (A) S2 cells expressing CAT-wt or CAT-72 mRNAs were treated with UPF1, UPF2 or UPF3 dsRNAs. Total RNA samples were analyzed by northern blot using probes specific for CAT and rp49 mRNAs. The numbers below the lanes indicate the levels of the CAT transcripts normalized to those of rp49 mRNA. (B) S2 cells expressing GFP-wt or GFP-52 mRNAs were treated with UPF1, UPF2 or UPF3 dsRNAs. The levels of the GFP transcripts normalized to those of rp49 mRNA are indicated below the lanes. (C) The levels of GFP-wt and GFP-52 mRNAs were quantitated in at least three independent experiments and normalized to those of rp49 mRNA. These ratios were set arbitrarily to 1 in control cells. The mean values ± SDs are shown. (D) S2 cell lines expressing GFP-wt or GFP-52 were treated with the dsRNAs indicated above the lanes. Total RNA samples were analyzed as described in (B).