The EUCOMM targeting vector PRPGS00036-W-3-B04 was used to create this conditional allele. The vector replaces exon 4 with an FRT site, lacZ sequence, loxP site, neomycin resistance gene under the control of the human beta-actin promoter, FRT site, and loxP-flanked exon 4. The lacZ and neomycin were removed via flp-mediated recombination in the ES cells leaving exon 4 floxed. (J:288987)