Fig. 5. Inclusion of either two (siC7/8) or three (siC10) CAG triplets at the 5' end of ataxin-3 small interfering RNAs (siRNAs) does not inhibit expression of unrelated CAG repeat-containing genes. (a) Western blot analysis of Cos-7 cells transfected with CAG repeat-GFP fusion proteins and the indicated siRNA. Shown is immunostaining with monoclonal anti-GFP antibody (MBL) at 1:1,000 dilution. siMiss, mistargeted siRNA. (b) Western blot analysis of Cos-7 cells transfected with flag-tagged ataxin-1-Q30, which is unrelated to ataxin-3, and the indicated siRNA. Immunostaining with anti-flag monoclonal antibody (Sigma) at a 1:1,000 dilution. In a and b, lysates were collected 24 h after transfection. Tubulin immunostaining is shown as a loading control.