UAS regulatory sequences drive expression of the full-length fj open reading frame, carrying amino acid substitutions (V87F and A91M) in two predicted sites for signal peptidase cleavage (a third potential signal peptidase cleavage site predicted in the ORF is not mutated). This results in impaired cleavage of the encoded protein; the cleaved C-terminus of fj was not detected in larval extracts expressing this transgene.