In contrast, through a series of in vitro and in vivo assays and experiments with clinical samples, mainly performed in the laboratory of Prof. Saya at Keio University, CD44 variant 9 (CD44v9), a splicing variant of CD44, has emerged as a novel marker of cancer stemness in a variety of solid tumors including HNSCC [14–18]. The gene discussed is CD44; the disease is head and neck squamous cell carcinoma.