Updated project metadata. Mice and other small mammals heavily rely on UCP1-mediated non-shivering thermogenesis in the cold, and thus the unexpected cold resistance of UCP1-knockout (UCP1KO) mice has always been and still is an unresolved mystery inextricably intertwined with alternative means of thermogenesis and futile substrate cycles. Several potentially thermogenic futile substrate cycles in adipose tissue of WT and UCP1KO mice have been reported in the literature. We hypothesized that isoproterenol treatment of brown adipocytes from UCP1KO mice would cause an immediate acceleration of futile substrate cycling, and entail a consecutive upregulation of the involved enzymes to recruit additional capacity. In this study, we analyzed changes in the proteome of wild type (WT) and UCP1KO adipocytes during acute adrenergic stimulation to detect characteristic molecular signatures, which allowed us to narrow down our search to potential candidates related to Ca2+ and lipid metabolism.