Aminoacyl tRNA synthase complex-interacting multifunctional protein 1 (AIMP1) is also known as multisynthase complex auxiliary component p43 and endothelial monocyte-activating polypeptide II (EMAP-II). AIMP1 is a cytokine that may be induced by apoptosis and is also released from professional antigen-presenting cells such as dendritic cells. The release of AIMP1 renders the tumor-associated vasculature sensitive to tumor necrosis factor. Furthermore, AIMP1 binds tRNA and stimulates the catalytic activity of cytoplasmic arginyl-tRNA synthase. This protein possesses inflammatory cytokine activity. Also, AIMP1 negatively regulates TGF-beta signaling through stabilization of SMURF2 by binding to SMURF2 and inhibiting its SMAD7-mediated degradation.