SIAH1 and neoplasm: TRAF4 is a novel substrate for SIAH1 and prevents SIAH1-mediated β-catenin degradation, the protective effect of TRAF4 on β-catenin during cellular stress, and linking TRAF4 to tumor chemoresistance, TRAF4 reduces the growth inhibitory effects of chemotherapeutic agents such as etoposide by reducing the number of S-phase cells and inhibiting apoptosis (50).