SMA-1 is required for proper intermediate filament arrangement. (a and a’’) Fluorescence of labeled EXC-2 (n = 20) and IFA-4 (n = 20) in wild-type background. (a’ and a’’’) Fluorescence intensity profile along the white line in the corresponding micrograph. (b–e) Fluorescence of labeled IFA-4 or EXC-2 in homozygous sma-1 or exc-4 backgrounds. (b’–e’) Fluorescence intensity profile along the white line in the corresponding micrograph. (b) IFA-4 fluorescence in sma-1(ru18) homozygous mutants (n = 25 animals examined). (c) IFA-4 fluorescence in exc-4(rh133) mutants (n = 25 animals). (d) EXC-2 fluorescence in sma-1(ru18) mutants (n = 25 animals). (e) EXC-2 fluorescence in exc-4(rh133) mutants (n = 25 animals).