Rearrangement and possible amplification of the ribosomal RNA gene sites in the human chronic myelogenous leukemia cell line K562.

We have studied the location of the nucleolar organizer regions (NORs) in the human chronic myeloid leukemia cell line K562. In man, the NORs are normally found on the short arms of the acrocentric chromosomes. We show that in the K562 line, the NORs are substantially rearranged with both insertional and terminal NORs. In addition, the putative t(15;17) marker chromosome had three insertional NORs that may have arisen through gene amplification.