B2M and head and neck cancer: Unlike head and neck cancer cell lines, TBP was stably expressed in A549 and NCI-H226 across all IR dose treatment groups while PP1A, GAPDH and B2M expression was exclusively expressed at 2, 4 and 6 Gy respectively (Fig. 2c,d, Supplementary Tables S15, S16, S17 and Fig. S4).