Ecsit is required for efficient assembly of mitochondrial NADH:ubiquinone oxidoreductase. Ecsit is an adapter protein of the Toll-like and IL-1 receptor signaling pathway that is involved in the activation of NF-kappa-B via MAP3K1.Ecsit promotes proteolytic activation of MAP3K1. Ecsit is involved in the BMP signaling pathway. Ecsit is required for normal embryonic development.