An amplification unit in human melanoma cells showing partial homology with sequences of human papillomavirus type 9 and with nuclear antigen 1 of the Epstein-Barr virus.

By partial homology with the DNA of human papillomavirus type 9 a cellular amplification unit was detected which is amplified in melanoma cells but not in Epstein-Barr virus-transformed B cells of two melanoma patients. A 2.4-kilobase EcoRI fragment of this amplification unit was cloned and designated mel/HPV9. At the chromosomal level we detected mel/HPV9 in homogeneously staining regions or in abnormally banded regions containing different marker chromosomes of both melanoma cell lines. DNA sequence analysis of a part of mel/HPV 9 revealed homology with the third internal repeat array of Epstein-Barr virus nuclear antigen 1.