CRISPR/cas9 genome editing used guide RNAs upstream (GTATTTACTAAAGGACTGTC and CTAAAGGACTGTCAGGAATC) and downstream (ATGAGCCTTCTTCCTAGGCC and CCTGTCAGAGATCCAGGCCT) to target exon 2. Donor DNAs were created to insert loxP sites flanking exon 2. (J:94077)