PRKAA2 and melanoma: To test our hypothesis, we generated Treg cell–specific AMPKα1- and AMPKα2-deficient mice (Prkaa1fl/flPrkaa2fl/flFoxp3YFP–Cre, referred to here as Prkaa1/2fl/flFoxp3YFP–Cre mice) and challenged them with either subcutaneous B16 melanoma tumors or intratracheal inoculations of influenza A/WSN/33 H1N1 virus, disease models whose outcomes are dependent on Treg cell function and whose microenvironments are burdened with metabolic derangements that challenge cellular metabolism (4, 23).