Although the CSCs surface marker are not well established in NPC cells by now, our recent investigations showed that CD44 was likely to be a desired surface CSC marker candidate in NPC cells.29, 30, 31 To confirm the relationship between ECM serglycin ligand and its receptor CD44, we examined their expression in 27 nasopharyngeal samples by using quantitative real-time PCR and found a strong positive correlation (r=0.58, P=0.002) (Figure 4a). The gene discussed is CD44; the disease is nasopharyngeal carcinoma.