DNA    amplifications    in
   neuroblastoma cells.

   Two  cancer genes (MYCN and MDM2) are amplified as small DNA fragments
   that remain separate from chromosomal DNA within the nucleus.
   Multiple copies of the MYCN gene are amplified within one large region
   called a heterogeneous staining region.

   Single  copies  of  the  MYCN  gene are visible on the normal parental
   chromosomes (white arrows).