UCP1 and neoplasm: Consistent with a decreased β-adrenergic tone, UCP-1 protein content was reduced in iWAT and aWAT depots of LLC tumor-bearing IL-4ra-KO mice compared with WT depots (Fig. 6C), corroborating the conclusion that IL-4ra–dependent IL-4 activation of macrophages regulates sympathetic activity and WAT browning.