Mammary lobuloalveolar development during pregnancy is controlled by the endocrine action of prolactin, estrogen and progesterone, but currently little is known of the transcriptional events that occur in response to these hormones. This study examines the transcriptional response of the mammary gland to the direct action of prolactin. Mammary tissue recombination experiments demonstrated that lobuloalveolar development is dependent upon the presence of prolactin receptors in mammary epithelium but not the ...