This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. The molecular lesion is a C to A substitution at coding nucleotide position 419 in exon 3 of the cDNA (c.419C>A, NM_009547). This changes the serine residue to a stop codon at position 140 of the encoded protein (p.S140*). (J:175213) Additional incidental mutations were detected in sequencing for the causative mutation, Zbtb14b2b1982Clo, and may be present in stocks carrying this mutation.