This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. The molecular lesion is a A to G substitution at coding nucleotide 1801 in exon 5 of the cDNA (c.1801A>G, NM_011841). This changes the threonine residue to alanine at position 601 of the encoded protein (p.T601A). (J:175213) Additional incidental mutations were detected in sequencing for the causative mutation, Mapk7b2b2346Clo, and may be present in stocks carrying this mutation.