Since the expression level of Ifnar (type I IFN receptor), but not the Ifngr (type II IFN receptor) or Ifnlr (type III IFN receptor), was increased (Figure 4B), we reasoned that type I IFN signaling pathway might play a role in Smad4KO‐mediated tumor inhibition. This evidence concerns the gene IFNGR1 and neoplasm.