IFNL1 and neoplasm: In the tumor context, IFN-λ activates IFNLR1-dependent caspase-3/8/9 signaling to induce G1/G0 cell-cycle arrest and apoptosis in colorectal cancer cells, exhibiting stronger cytotoxicity than IFN-I or IFN-II (198), consistent in vitro and in vivo evidence that recombinant IFN-λ1 suppresses tumor growth in a dose-dependent manner (199).