MPPE1 and neoplasm: Our results indicate STAT3 signaling within CD103+ cDC1s elicits immunosuppressive responses including restrained expression of T cell co-stimulatory molecules and cytokines, as well as suppressed CD103+ cDC1-mediated increases in tumor antigen-specific CD8+ T cell and Th1 cell subsets in vivo (Figure 1, Figure 3A,B, Figure 4 and Figure S2A,B).