NOTCH1 and head and neck squamous cell carcinoma: This study provides original evidence demonstrating that CAF-secreted factors sustain and robustly enhance stemness in HNSCC-derived cell lines, thereby increasing anchorage-independent growth, tumorsphere formation, and expression of various CSC markers, such as NANOG, SOX2, OCT4, ALDH1, CD133, CD44, and NOTCH1, in the absence of serum or any other supplements.