Cluster analysis about mRNA expression between TRAF6 and some common EMT and CSC markers has been operated; result showed that TRAF6 and EMT and CSC mRNAs in SCCHN are correlated (Fig. S1B), especially a strong correlation with CD44. Tgfbr1 and Pten knockout mice with de novo SCCHN tumorigenesis have been reported in our previous study 38. Here, CD44 is linked to head and neck squamous cell carcinoma.