Fig. 3. High-level expression of FP-SMN leads to cytoplasmic accumulation of SMN-complex proteins and disruption of nuclear structure. Three-dimensional projections of serial sections showing HeLa cells and MCF-7 cells expressing high levels of GFP-SMN following transient transfection. All cells show cytoplasmic accumulation of GFP-SMN (arrows in C, F and I). These accumulations also contain SIP1/Gemin2 (A-F) and Sm proteins (G-I). They do not contain TMG-capped RNA (J-L) or coilin (M-O). Many cells also show a large number of small nuclear bodies containing GFP-SMN, TMG-capped RNA and coilin (arrows in L and O). Bar, 10 µm.