Among them, a heterozygous point mutation of p53 gene at codon 280 from AGA to ACA (Arg changed to Thr) (R280T) was identified in the five NPC cell lines (CNE1, CNE2, TW06, TW01, and HONE1), with a mutation rate of about 10% in NPC tissues (15, 17–19). This evidence concerns the gene TP53 and nasopharyngeal carcinoma.