the next several years, and it was through experimentation on LP and hormone interaction that his most renowned discovery was made. After identifying the importance of LP, Sutherland moved his research efforts to Western Reserve University. There, he worked in collaboration with Ted Rall, Walter D Wosilait, and Jacques Berthet to publish a series of papers in the Journal of Biological Chemistry, "The Relationship of Epinephrine and Glucagon to Liver Phosphorylase", which was released in four parts. These four papers document the purification of LP and the analysis of several of its properties. First, it was determined that the enzymatic activity of LP depends on the addition or removal of a phosphate group, a process called phosphorylation. In a later experiment, they demonstrated that more phosphate is taken up in liver slices when epinephrine and glucagon are added, suggesting that these hormones were promoting the phosphorylation of LP, activating the enzyme. The results of a later paper in the series suggested that this phosphorylation and activation of LP was a result of the action of phosphorlyase kinase. This series also investigated the inactivation of liver phosphorylase and characterized an enzyme they initially called LP-inactivating enzyme, which functions by cleaving the phosphate group. This enzyme was later renamed liver phosphorylase phosphatase. These papers also characterized LP in terms of molecular weight and other factors. During their analysis, they found the unexpected result that LP activation increased with the addition of 5-AMP, which is a precursor of cAMP; however, this was not known at the time. The fourth paper published in this series, "The Relationship of Epinephrine and Glucagon to Liver Phosphorylase: IV Effect of Epinephrine and Glucagon on the Reactivation of Phosphorylase in Liver Homogenates", was published in 1956. In this paper, Sutherland and associates furthered their investigation of epinephrine and glucagon. The key to the success of this experiment was the use a homogenate of liver cells rather than intact liver cells, as they had been doing in their previous experiments. The general consensus among researchers at that time was that the study of hormones was only possible using intact cells; this was the first instance that a hormone pathway was studied using a cell homogenate. Sutherland and his co-authors were able to observe similar effects in liver homogenate to what was observed in whole liver slices. More importantly, they were able to observe this response in two stages. This