This allele results after the cre mediated excision of the neomycin resistance cassette in Surf1tm2Zev. The loxP remaining in exon 7 disrupts the reading frame from nucleotide 674 downstream of the cDNA and the replacement of the codon encoding N225 with a TAA stop codon. This frame shift would putatively result in the elimination of 81 amino acids from the carboxy terminus, however, no protein was detected by Western blot.