NFKB1 and neoplasm: Furthermore, to exclude the possibility that this difference in HIF-1α immunoreactivity is correlated with the size of xenograft tumours rather than NF-κB activity, we compared HIF-1α expression in three sets of similarly sized xenograft tumours: the sizes of SNU-668IκBαM tumours were 251.2, 255.2, and 255.8 mm3, and the sizes of corresponding vector control tumours were 255.4, 256.3, and 259.5 mm3.