Amino acid replacement: M469K.
Nucleotide substitution: T1406A.
Adults carrying fz50E1.Act5C in a fz21 background have an average of 2.3 +/- 0.5 extra tarsal joints in the leg compared to wild type.
fz50E1.Act5C shows poor rescue of the wing margin phenotype of fz21 fz2C1 double homozygous clones.