KRT15 and head and neck squamous cell carcinoma: We then examined the expression levels of canonical marker genes for aggressive human HNSCC (KRT14, KRT17, KRT6A, KRT5, KRT19, KRT8, KRT16, KRT18, KRT6B, KRT15, KRT6C, KRTCAP3, EPCAM, SFN)46 and found that this 12-gene signature was expressed primarily by cells in clusters 2 and 10 (Fig. 4b).