**11. Conclusion**

 In conclusion, it is likely that docetaxel suppresses SCC migration through inhibition of microtubule turnover, which affects cdc42 activity and its subcellular localization leading to decreased filopodia formation. We propose that effect on cancer cell migration should be assessed together with anti-proliferative activity when evaluating a cancer chemotherapeutic agent. Along this line, we are now evaluating anti-migratory effect of EGFR tyrosine kinase inhibitors, another class of promising treatment for head and neck cancer.
