NOS2 and neoplasm: To examine whether the radiosensitivity of iNOS-expressing tumour cells may be altered by NF-κB inhibitors, EMT-6 cells were pretreated for 3 h with 40 μM lactacystin or for 10 min with 4 μM PAO and afterwards exposed to 0.1 μg ml−1 LPS in hypoxia.