Adaptive epigenetic changes and toxicity often accompany constitutive expression of a
transgene or knockout of an endogenous gene in mice. These considerations potentially
limit the usefulness of transgenic technology in studying the in vivofunctions of a gene.
Using conditional gene expression technology, it is possible to override such restrictions to
achieve temporal and tissue-specific manipulation of gene expression in vivo. Based on the
tetracycline regulatory system, we established a binary transgenic model in which the …