TRIM38 (tripartite motif containing 38) is an E3 ubiquitin-protein and E3 SUMO-protein ligase that serves as a critical regulator of innate immunity and cellular homeostasis 1. The protein functions as both a positive and negative regulator of immune signaling pathways depending on the context. TRIM38 negatively regulates type I interferon production by catalyzing K48-linked polyubiquitination of TICAM1, inhibiting TLR3-mediated signaling, while also acting as a positive regulator of the cGAS-STING pathway through sumoylation of CGAS and STING 1. In antiviral responses, TRIM38 restricts Zika virus replication by upregulating the RIG-I/MDA5 pathway, increasing IFN-β levels, and degrading viral NS3 protein through its E3 ligase activity 2. Beyond immunity, TRIM38 functions as a tumor suppressor in colorectal cancer by promoting K48-linked ubiquitination and degradation of CCT6A, which subsequently reduces c-Myc protein levels and inhibits the MYC pathway 3. In breast cancer, TRIM38 suppresses progression by promoting non-degradative K63-linked ubiquitination of SQSTM1/p62, disrupting autophagy 4. TRIM38 also regulates macrophage polarization by stabilizing HSPA5 through K63-dependent ubiquitination, promoting M2 macrophage markers and reducing hepatic inflammation 5.