Monitoring RhoGTPase Activity in Leukocytes Using Classic “Pull-Down” Assays

Inflammation is a complex process involving the contribution of leukocytes and blood vessels, which collectively aim to restore homeostasis following injury to the body. Leukocytes are essential front-line responders to infectious or noninfectious injury and can be deployed within minutes of sensing damage. A typical inflammatory response leads to the exit of circulating leukocytes into the surrounding extravascular space, which follows a series of increasingly adhesive events - collectively termed the "multistep adhesion cascade." The Ras homology (Rho) family of small GTPases (RhoGTPases) are intracellular proteins involved in translating extracellular signals into cellular behavior, such as adhesion and migration. This chapter focuses on how to prepare, perform, and monitor RhoGTPase activation assays using classic pull-down assays. Although this chapter focuses on RhoGTPase signaling downstream of L-selectin clustering, the methods outlined here can be applied to analyzing RhoGTPase activity in response to stimulating other surface receptors.