A sequence cassette has been introduced into the attP site present in TI{TI}LkrattP, restoring the deleted Lkr sequence and inserting a 2A-EGFP sequence at the C-terminal end of the open reading frame. In addition, two FRT sites have been inserted, one at the N-terminal end of the reintegrated sequence, and the other downstream of the 2A-EGFP sequence (a single loxP site is also present, downstream of the second FRT site). This results in a conditional allele; FLP recombinase can be used to excise the artificial FRT cassette, excising the 2A-EGFP sequence and removing Lkr coding sequence, disrupting its function.