BMI1 and nasopharyngeal carcinoma: We also examined KLHDC4 expression in 10 nasopharyngeal epithelial cell lines, including 3 immortalized normal nasopharyngeal epithelial lines (NP69, NPEC-N2-Bmi1 and NPEC-N5-Tert) and 7 nasopharyngeal cancer lines (CNE1, CNE2, SUNE1, SUNE2, HK1, HNE1 and HONE1).