ECHS1 interacts with STAT3 and negatively regulates STAT3 signaling

► ECHS1 interacts with STAT3 in vitro and in vivo. ► ECHS1 inhibits the transcriptional activity of STAT3 induced by IL-6 and EGF. ► ECHS1 decreases STAT3 tyrosine phosphorylation. ► ECHS1 negatively regulates expression of STAT3 target genes. ► We identify a novel STAT3 binding protein and reveal a new biological function of ECHS1 as regulator of STAT3 signaling.