ETV3 is a transcriptional repressor that plays critical roles in myeloid differentiation and immune tolerance. Primary function: ETV3 acts as a sequence-specific DNA-binding transcription factor that represses target genes involved in proliferation and cell fate decisions 1. Mechanism: ETV3 controls monocyte differentiation into dendritic cells by directly repressing MAFB expression and inhibiting macrophage fate commitment, independent of interferon signaling 1. In mature dendritic cells, ETV3 facilitates homeostatic maturation and CCR7-dependent migration while suppressing costimulatory molecules like OX40L, thereby maintaining tolerogenic function 2. Disease relevance: ETV3 genetic variants are associated with systemic lupus erythematosus; Etv3-deficient mice show spontaneous T cell activation and multiorgan infiltration with exacerbated SLE-like disease 2. ETV3 is also implicated in hematologic malignancies, including ETV3-NCOA2 fusion in indeterminate dendritic cell histiocytosis 3, ETV3 genomic duplication in Hodgkin lymphoma 4, and copy number gains in breast cancer correlating with ETV3 overexpression 5. Clinical significance: ETV3 represents a therapeutic target for redirecting monocyte differentiation in inflammatory disorders and may inform treatment strategies for dendritic cell-derived malignancies and autoimmune conditions.