USP18 and neoplasm: However, NF-κB is known to be one of the key transcription factors related to polarization toward anti-tumor/pro-inflammatory macrophages.56 NF-κB regulates the expression of a large number of inflammatory genes, including TNF-α, IL-1β, cyclooxygenase-2 (COX-2), IL-6, and IL-12p40.57 Therefore, it is likely that anti-tumor/pro-inflammatory macrophage polarization observed in USP18-KO macrophages also relies on the NF-κB pathway in addition to the CSF1R-mediated regulation.