To obtain a more complete understanding of the varied effects of the respective mTOR-Is + IR, we investigated their impact on the downstream protein S6 by measuring its levels of phosphorylation via the IS of p-S6 in UM-SCC-47 HNSCC tumor cells over a period of 0 to 16 h after IR exposure (Figure 7A) [64]. Here, MTOR is linked to head and neck squamous cell carcinoma.