NFKB1 and head and neck squamous cell carcinoma: Since NF-κB is a master regulator of acute SASP cytokine production [20] and our clonogenic survival experiments have shown that inhibition of NF-κB by metformin interferes with inherent as well as conditioned radioresistance in our HNSCC models (Fig. 2G), we next analyzed cytokine production by radioresistant UPCISCC 040 cells upon ionizing irradiation in the presence or absence of metformin.