To test whether CD103+ cDC1 vaccination induces similar responses in murine breast cancer, and if STAT3 modulates CD103+ cDC1-mediated immune responses, we evaluated immune cell populations within tumors and TdLNs following vaccination of mice bearing bilateral PyMT-OVA tumors with Stat3fl/fl or Stat3∆/∆ CD103+ cDC1s. Here, MPPE1 is linked to breast cancer.