NFKB1 and neoplasm: Given that living tumour cell repopulation stimulated by dying tumour cells via cytotoxic treatment‐induced ER stress, to identify the molecular events in living tumour cells, we estimated the transactivation of several transcription factors in SCC‐25 cells after coculture with cDDP‐treated feeder cells and demonstrated that NF‐κB signalling showed the greatest activation (Figure S4A).