Furthermore, when DCs were incubated with culture medium supernatant of tumor cells, the percentage of CD80+ cells also increased by supernatant from Smad4KO but not WT PDAC cells, nor Smad4&StingKO cells (Figure S6C, Supporting Information), indicating the essential role of tumor‐intrinsic STING‐mediated signaling in DC activation. Here, SMAD4 is linked to neoplasm.