Tag:HA-tagged Xrp1 exon 7 sequence (the last exon of the gene) has been reintroduced into the attP site present in TI{TI}Xrp1attPloxP, resulting in a Xrp1 locus that encodes the wild-type protein tagged at the C-terminal end with Tag:HA. Due to the reintegration event, an attL site is present upstream of Xrp1 exon 7 and a sequence cassette comprised of the following is present downstream of Xrp1 exon 7: a loxP cassette (containing a w+* marker and an ampicillin resistance gene), an attR site, and a duplicated copy of Xrp1 exon 7.