9306493 Fleming An important function of estradiol(E2) is to regulate growth and differentiation of endometrial cells by causing changes in their RNA transcriptional program. Experiments are planned to allow detection of changing mRNA levels in cultured human endometrial cells in response to physiological concentrations of E2. The Ishikawa cell line has been shown to retain its ability to respond to E2: proliferation can be stimulated and specific proteins can be induced. Changing levels of mRNAs will be studied in a systematic way during the first 24 hours following the addition of E2. Other mRNAs (secondary responses) will not appear for many hours because their induction requires the synthesis of a protein induced as part of the primary response. Experiments are suggested to detect these two different classes of mRNA. Additional experiment are planneed to look for other classes of mRNAs induced by E2 in these cells and to study and compare characterstic responses of different classes of mRNA to different inhibitors. ***