Abstract
Rac1 is a member of the family of small Rho GTPases that are molecular switches governing a variety of fundamental cellular processes, such as cell growth and motility. Its subcellular location and activity are regulated by several posttranslational modifications. S-glutathionylation, the adduction of glutathione to cysteine residues in Rac1, is a redox-dependent thiol modification and is generally associated with oxidative/nitrosative stress, representing a novel mechanism of GTPase regulation. Here, we describe the use of biotin-labeled glutathione to monitor intracellular glutathionylated Rac1 in response to exogenous stimuli.