This application seeks to examine regulation of myometrial OTR expression in a murine model. Specifically, the investigator will 1) define the molecular organization and regulatory regions of the mouse OTR gene by genomic cloning, DNA sequence analysis, and identification of putative transcription factor consensus sequences; 2) test putative cis-acting OTR gene regulatory elements in vitro via quantitation of OTR-luciferase reporter gene expression in transfected primary myometrial myocytes and cell lines, and modulation by estrogenic steroids; and 3) define the genetic information required for spatial, temporal, and estrogen (E) regulation of the native OTR gene in transgenic mice that express an OTR-beta-galactosidase reporter gene.