Figure 1. Diagram of KC (Kera-Cre) minigene construct. An expression DNA construct was prepared with pBskII plasmid (Strategen, La Jolla, CA) using conventional cloning strategy, which contained 3.2 kb of 5′ DNA fragment upstream of the transcription initiation site, 172 bp of exon 1, the full length of intron 1 (1.4 kb), and 7 bp of exon 2 preceding the ATG starting codon of Kera, and an IRES-NLS-Cre minigene. The minigene was released by Not1 and Fsp1 restriction enzyme digestion and used in the microinjection of fertilized eggs by Transgenic Core at the Children’s Hospital of Cincinnati.