Transgenic Mouse Core The mouse core is devoted to breeding of all non-commercially available murine lines, and the maintenance and distribution of these mice for use in experiments required to achieve the aims of this Program. In addition, the core will absorb all animal care costs generated by these projects. The existence of such a core is justified by the significant overlap among investigators of transgenic lines used in the various projects, and the fact that many experiments will be performed as collaborative efforts. It is anticipated that there will be qual use of the animal core by all investigators.