The Buck and Levin lab focus on the second messenger molecule cAMP, which modulates cell growth and differentiation in organisms from bacteria to higher eukaryotes. cAMP is produced by adenylyl cyclases, and mammals possess two distinct classes of adenylyl cyclase, the hormone-responsive, transmembrane adenylyl cyclases (tmAC) and the bicarbonate-regulated Soluble Adenylyl Cyclase (sAC). The Levin-Buck laboratory purified and cloned sAC, and sAC is now studied in the combined “LevBuck” laboratory.