NFKB1 and neoplasm: Considering that the expression of Hmox1 is also regulated by the pro-inflammatory transcription factor nuclear factor κB (NFκB) and activator protein 1 (AP1)32, and that Hmox1 is known to be upregulated in inflamed colonic tissues33, we speculate that the enhanced Hmox1 expression in the tumors is at least in part due to the markedly enhanced inflammation in tumor compared to peri-tumoral tissue (Fig. 3a–c).