Amplification of the c-myc oncogene in human plasma-cell leukemia.

We have examined primary leukemia cells from multiple myeloma and plasma-cell leukemia patients for rearrangement, amplification and expression of c-myc oncogene. No rearrangement or detectable amplification of the c-myc could be found in 21 cases of multiple myeloma. In contrast, 2/3 cases of plasma-cell leukemia showed amplification of the oncogene with concomitant higher level of expression.