RPS6KB1 and head and neck squamous cell carcinoma: Further, inhibitory effect of honokiol on EGFR in tumor xenografts was also associated with reduced expressions of mTOR and its down-stream target proteins p70S6K and 4E-BP1, suggesting the involvement of these molecular targets in preventing the in vivo growth of HNSCC xenografts by honokiol in mice (Figure 6D).