NRG4 and metabolic disease: These observations provided additional, stronger evidence to support previous findings from our (Cai et al., 2016) and other studies (Wang et al., 2014; Dai et al., 2015; Jiang et al., 2016; Chen et al., 2017; Yan et al., 2019) that brown fat-enriched secreted factor Nrg4 is involve in crosstalk between adiposity and metabolic disorders.