Heterozygous mice for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. Homozygous mice are embryonic lethal.

B-UBC-iCre mice(+/+); B-CAG-tdTomato cKI mice(+/+): No tdTomato positive signal was detected in any of the examined tissues, including the heart, liver, spleen, lung, kidney, brain, intestine, and eye. Note: (+/+) indicates the wild-type genotype at the B-UBC-iCre mice locus (i.e., absence of Cre) and B-CAG-tdTomato cKI mice locus, serving as the negative control.

B-UBC-iCre mice(Mut/+); B-CAG-tdTomato cKI mice(Δ/+): Significant brown positive signals were observed in all examined tissues (heart, liver, spleen, lung, kidney, brain, intestine, and eye), indicating ubiquitous expression of the tdTomato protein. Note: (Mut/+) indicates the presence of Cre recombinase; (Δ/+) indicates the successful excision of the Stop sequence.