UASt regulatory sequences drive expression of sns, in which 17 Ser residues have been mutated (amino acid replacements S1131A, S1132A, S1143A, S1144A, S1146A, S1149A, S1151A, S1153A, S1157A, S1158A, S1172A, S1179A, S1236A, S1238A, S1246A, S1252A and S1257A). The coding sequence is tagged at the C-terminal end with a single Tag:HA tag.