IF/FISH targeting myogenin (IF) and the (CAG)-repeat (FISH) of transduced DM1 fibroblasts. (A and E) Panels display DAPI counterstain, (B and F) FITC/GFP channel, (C and G) Cy3 channel, (D and H) merge of DAPI/GFP/Cy3. (A-D) Cells transduced with GFP display no change in morphology or in the number of Cy3-foci (red) top panel. (E-H) Cells transduced with myoD display a multinuclear morphology, signs of cell fusion (syncytia), and an increased number of Cy3-foci per nucleus. Primary antibodies target myogenin, secondary antibodies are Alexa Fluor 488-labeled. The probe is a Cy3-labeled (CAG)10 DNA oligonucleotide. Original magnification × 630.