The transgenic model being generated is a strain of transgenic (TG) mice designed to express the mouse AF2ER mutant protein in a global or tissue specific manner by crossing with Cre expressing mice. Once the TG is incorporated this TG mouse will express beta galactosidase (LacZ) in the TG before crossing with Cre mice, after which the TG construct is activated to express the mutated ERa (AF2ER) protein. We will characterize the functionality of the AF2ER mutant receptor protein in specific tissues by the crossing with tissue specific Cre expressing mice or by way of a cross with a global expressing mouse line such as Sox2-Cre.