Description: Monensin is an inhibitor of intracellular protein transport. Incubation of cells in culture with Monensin leads to blockade of protein transport to the Golgi complex (GC) and accumulation of proteins in the endoplasmic reticulum (ER). Addition of Monensin during the last hours of in vitro activation of cells results in enhanced detection of intracellular cytokines. Monensin is effective for enhanced detection of a majority of mouse and human intracellular cytokines; however, it is advised that the investigators evaluate the use and efficacy of this reagent as well as other protein transport inhibitors such as Brefeldin A in their specific assay system.