A sequence cassette encoding T2A-QF2 (with an Hsp70 terminator sequence) followed by a loxP cassette containing a Disc\RFPDsRed.3xP3.cUa marker has been inserted into the endogenous CG9458 locus. The cassette was inserted via the CRISPR/Cas-9 drop-in technique, using a dsDNA donor vector with homology arms of length 200bp. The sgRNA sequence used to target the gene was: TTTCGATTCCGCATGATCTT.