Figure 2. Detection of HPV PCR products with agarose gel electrophoresis in representative examples. The housekeeping gene was positive in all samples; human papilloma virus (HPV) was positive in the positive control but negative in the adenoid cystic carcinomas (ACCs). TBXAS1: Housekeeping gene PCR product, 100 bp; MGP: Modified general primer HPV PCR product, 158–168 bp; M: Molecular weight ladder; 1: Positive control, condyloma acuminatum; 2–9: Representative examples of ACCs.