LoxP sequences flanking exons 11 to 14 of the mouse histone deacetylase 3 gene and loxP sequences flanking the Neo expression cassette was targeted to mouse histone deacetylase 3 gene. In-vitro mediated cre-deletion resulted in excision of exons 11 to 14 of histone deacetylase 3 gene including the neo cassette. (J:147112)