HEK293FT cells expressing mutant SOD1 proteins do not form visible cellular inclusions. A-I) Cells were cultured on glass coverslips previously coated with 0.5 mg/ml poly-L-lysine untransfected (A, B), or transfected with expression plasmids for WT (C, D) or A4V (E, F) SOD1 for 24 hours. Fixed cells were stained with hSOD1 antibody overnight. A secondary fluorescent (594 nm) antibody was used to visualize SOD1 antibody binding. Co-staining with 4',6-diamidino-2-phenylindole (DAPI) was performed together with secondary antibody incubations. Pictures were taken with a 100× immersion oil objective, scale bar = 20 μm. Note that at the same exposure, the staining of overexpressed hSOD1 protein is much brighter than that of untransfected cells (compare figure A to C and E). The images shown are representative of at least 3 independent transfection experiments.