This brochure briefly summarizes what is currently known about the cytokines belonging to the common cytokine receptor gamma-chain family, which includes IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. It provides a brief overview of the signaling pathways that are activated in response to each of these cytokines and a description of the primary biological effects that they induce. Additionally, it describes the tools that we offer for research on this cytokine family including: