“To confirm this result, we established shhact/+fish carrying the transgene Tg(ubb:iCRE- GFP) (ubb:Cre-GFP), in which codon-improved Cre (iCRE) DNA was expressed by a strong, ubiquitously expressed ubiquitin B (ubb) promoter (Mosimann et al., 2011) (Figure 2—figure supplement 1A). […] We also performed semi-qRT-PCR analysis of shha expression and confirmed that its expression was reduced to nearly 50% of WT levels in the heterozygous mutants and to an undetectable level in the homozygous mutants (Figure 3—figure supplement 2D and E).”