<；P>；PROBLEM TO BE SOLVED: To provide a gene homo-modified mammal cell in which arbitrary gene of somatic cell applicable also to other kind of mammal (livestock, etc.) other than mouse is modified to homo in a recombinant genome and to provide a method for efficiently creating a homo-modified nonhuman mammal and to provide a homo-modified mammal cell or a homo-modified nonhuman mammal established or created by the method. <；P>；SOLUTION: A targeting vector in which a resistant gene unit is removably integrated after targeting operation is built and a first targeting operation is carried out by using the target vector to acquire a hetero-modified mammal cell and the resistant gene unit is eliminated by resistant gene unit-eliminating operation and a second targeting operation is carried out to establish the homo-modified mammal cell of arbitrary gene of somatic cell. The homo-modified nonhuman mammal in which an arbitrary gene is modified to homo is created by using the established cell. <；P>；COPYRIGHT: (C)2007,JPO&INPIT
