A TI{CRIMIC.TG4.0} DNA cassette has been inserted into Cyt-b5, in a coding intron, and is predicted to gene trap all annotated transcripts of the gene. The TI{CRIMIC.TG4.0} 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: TGTCTGGTCCATGAAATTCAGGG. The PCR check of the insertion gave no band for the left flank and the expected sized product for the right flank. The insertion junction of the right flank was verified by sequencing.