In addition, ISG15 mRNA and protein levels were elevated in multiple NPC cell lines, such as SUNE2, 6-10B, S26, CNE1, CNE2, HNE1 and HONE1, compared with immortalized NPECs, NPEC1-Bmi1 and NPEC2-Bmi1 (Figure 1C and 1D). Here, ISG15 is linked to nasopharyngeal carcinoma.