UASp regulatory sequences drive expression of a chimeric protein consisting of amino acid residues 1-172 of cid (the N-terminal region up to helix 2 in the histone fold domain), helix 2 of the histone fold domain of His3, and amino acids 201-225 of cid (the part of cid C-terminal to helix 2). The protein is tagged at the C-terminal end with 10 copies of Tag:MYC.