Exon 10 was replaced with a floxed neo cassette and a modified exon 10 in which a C to T transition results in the amino acid substitution of leucine for proline at position 301 (P301L). Cre-mediated recombination removed the neo cassette. A 35 kb tandem duplication spans exons in the 3' ends of Mapt and Kansl1. Transcript expression is not effected by this duplication. (J:188213)