The cDNA encoding Prkcz followed by a floxed neomycin resistance cassette was inserted into the coding sequence of exon 2. Cre-mediated recombination removed the neomycin resistance cassette. This allele expresses a fusion protein consisting of the first 28 amino acids of the endogenous sequence and the remaining 564 amino acids of the knocked-in sequence. Western blot analysis confirmed the absence of endogenous protein expression and expression of the knock-in sequence in E9.5 embryos.