Fig. 4. FRAP analysis reveals an immobile fraction of GFP-MBNL1 molecules in both CUG and CAG foci. COSM6 cells were transfected with GFP-MBNL1 alone or with DMPK minigenes containing 960 CTG or CAG repeats. (A) Photobleaching of foci and nucleoplasm in 960 CUG repeat and CAG repeat or 0 repeat plasmids. White circles denote the photobleached regions in the foci and nucleoplasm. Bars, 10 µM. (B) Recovery curves of photobleached foci and nucleoplasm in cells expressing CUG or CAG repeats. Five images were taken pre-bleach, followed by bleaching pulses as indicated on the graph. The half-time of recovery was calculated from at least three independent experiments. The duration of the experiment was 100 seconds. The graph represents the data collected from 42, 34 and 45 cells for the expression 960 CUG repeats, 960 CAG repeats and GFP-MBNL1, respectively. RFI, recovery of fluorescence intensity.