TNF and neoplasm: Interestingly, this in vivo NF-κB response of KRASMUT cells was abolished in IL-1β-deficient (Il1b−/−31), but not in TNF-deficient (Tnf−/−32), mice (Fig. 3b), indicating that KRASMUT tumor cells selectively respond to IL-1β of the pleural environment by activating NF-κB.