This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. It is a subline of b2b3077Clo. The molecular lesion for this subline is a G to T substitution at coding nucleotide 670 in exon 4 of the cDNA (c.670G>T, NM_009524). This changes the glutamic acid residue to a translation stop at position 224 of the encoded protein (p.E224*).