numb-RA sequence (5' UTR, coding region and 3'UTR) that is tagged at the C-terminal end of the coding sequence with GFP has been reintroduced into the attP site present in TI{TI}numbcrispr. Due to the reintegration event, an attL site is present upstream of the reintegrated numb-RA sequence, and a sequence cassette comprised of the following is present downstream of the reintegrated numb-RA sequence: a loxP site, a w+* marker, an attR site, another loxP site, the Disc\RFPDsRed.3xP3.cUa marker that was present on the progenitor TI{TI}numbcrispr chromosome, and a third loxP site.