UASt regulatory sequences drive expression of a mutated form of ci in which phosphorylation cluster 2 has been converted to a single DSGXXS motif (present in arm), but with the S residue in the DSGXXS motif mutated to A, followed by an engineered PKA site C-terminal to it and in which the PKA site in phosphorylation clusters 1 and 3 has been mutated to Ala to prevent any phosphorylation of these clusters (amino acid replacements S838A and S892A respectively). The coding sequence is tagged at the N-terminal end with two copies of Tag:HA.