Western blotting and quantitative real-time PCR was applied to analysis the expression levels of PTP4A2 protein and mRNA in five NPC cell lines (CNE1, CNE2, C666, HONE1 and SUNE1) and one immortalized primary nasopharyngeal epithelial cell line (NPEC2 Bmi-1). This evidence concerns the gene BMI1 and nasopharyngeal carcinoma.