Southern hybridization of cellular sequences flanking integrated HPV18 in cervical carcinoma. Alu-PCR products were hybridized with an HPV18-specific oligonucleotide probe. Lanes 1 and 2, HPV18(+) cervical squamous-cell carcinoma; lane 3, HPV18(+) cervical adenocarcinoma; lane 4, HPV16(+) cervical squamous-cell carcinoma; lane 5, normal human genomic DNA; lane 6, Alu-HPV18 hybrid plasmid (2.3 kb); and lane 7, negative control. Tumors 1 and 2 harbored multiple HPV18 integrations.