Sequence encoding ex binding region 1 (EBR1) and sequence encoding ex binding region 2 (EBR2) has been deleted from the endogenous ft locus (deleted amino acids are LNSPVMSQLSGQSSS and SATTLGWEYLLNWGPSYENLMGVFKDIAELPDTNGPSQQQQ). Three copies of Tag:FLAG have been inserted at the C-terminal end of the coding sequence.