Glutathione-S-transferases (GSTs) are a family of Phase II detoxification enzymes that catalyze the conjugation of glutathione (GSH) to various electrophilic compounds. GSTs are divided into microsomal and cytosolic families, with the latter being highly polymorphic and classified into six classes: α, μ, ω, π, θ, and ζ. The π and μ classes of GSTs play a regulatory role in the mitogen-activated protein (MAP) kinase pathway, influencing cellular survival and death signals. GSTs have been implicated in the development of drug resistance, acting both as direct detoxifiers and inhibitors of the MAP kinase pathway. The link between GSTs and the MAP kinase pathway explains why many drugs used to select for resistance are not substrates for GSTs. GSTs have emerged as promising therapeutic targets due to their overexpression in various tumors and their potential role in other diseases. Therapeutic strategies include GST inhibitors, compounds that disrupt protein-protein interactions, and GST-activated prodrugs. Prodrugs activated by GSTs have shown clinical efficacy in treating drug-resistant cancers, and ongoing Phase III studies are evaluating their combination with other agents.Glutathione-S-transferases (GSTs) are a family of Phase II detoxification enzymes that catalyze the conjugation of glutathione (GSH) to various electrophilic compounds. GSTs are divided into microsomal and cytosolic families, with the latter being highly polymorphic and classified into six classes: α, μ, ω, π, θ, and ζ. The π and μ classes of GSTs play a regulatory role in the mitogen-activated protein (MAP) kinase pathway, influencing cellular survival and death signals. GSTs have been implicated in the development of drug resistance, acting both as direct detoxifiers and inhibitors of the MAP kinase pathway. The link between GSTs and the MAP kinase pathway explains why many drugs used to select for resistance are not substrates for GSTs. GSTs have emerged as promising therapeutic targets due to their overexpression in various tumors and their potential role in other diseases. Therapeutic strategies include GST inhibitors, compounds that disrupt protein-protein interactions, and GST-activated prodrugs. Prodrugs activated by GSTs have shown clinical efficacy in treating drug-resistant cancers, and ongoing Phase III studies are evaluating their combination with other agents.