Mice carrying a targeted mutation in their Adam11 gene were generated by homologous recombination (Fig. 1A). Correct targeting events were confirmed by Southern blot analysis (Fig. 1B). As a result of this procedure, since a termination codon was introduced in exon 5 in the pro-protein domain, only the truncated form of the ADAM11 protein would be synthesised from this targeted allele. Because pro-protein domains are always removed in mature functional ADAM-proteins by furin-like proteases and are thus thought to be non-functional, we concluded that this truncated form of ADAM11 protein would have no function [26]. Absence of mature ADAM11 protein in homozygous mutants was confirmed by Western blot analysis using a specific antibody that recognises the ADAM11 protein (Fig. 1C). Analysis by Western blot showed that heterozygous mutants produced approximately half of the wild-type levels of ADAM11 protein.