A loxP site was inserted upstream of exon 9 and an FRT flanked neo cassette and loxP site were inserted downstream of exon 9 via homologous recombination. Flp and cre mediated recombination removed the neo cassette and exon 9. This results in a frame-shift mutation after amino acid 284 that eliminates the majority of functional domains, creating a loss-of-function allele. The CG-1 domain contained within the residual portion of the mutated gene is not expected to function as a dominant-negative mutant. (J:212232)