CD44 and head and neck cancer: Flow cytometric analysis showed that a small population of SCC-1 cells (∼7-8%) was positive for CD44 (Figure 2A), a commonly used cell surface marker for head and neck cancer stem-like cells [19, 22], while EGF stimulation upregulated CD44 expression and significantly enriched the fraction of CD44+/CD24low/− cells (Figure 2A).