Diminished Milk Synthesis in Upstream Stimulatory Factor 2 Null Mice Is Associated With Decreased Circulating Oxytocin and Decreased Mammary Gland Expression of Eukaryotic Initiation Factors 4E and 4G

Abstract
Previous studies have suggested that upstream stimulatory factors (USFs) regulate genes involved with cell cycle progression. Because of the rela- tionship of USFs to an important oncogene in breast cancer, c-myc, we chose to determine the importance of USF to normal mammary gland de- velopment in the mouse. Expression of USF in the mammary gland throughout development demon- strated only modest changes. Mutation of the Usf2 gene was associated with reduced fertility in fe- males, but had no effect on prepartum mammary gland development. However, lactation perfor- mance in Usf2/ females was only half of that observed in Usf2/ females, and both lactose and nitrogen were decreased in milk from Usf2/