Amplification
Making multiple copies of a gene or of any sequence of DNA.
Repeated copying of a piece of DNA.
In amplification there is an increase in the number of copies of any particular piece of DNA.
Gene amplification plays a role in cancer cells.
A tumor cell amplifies, or copies, DNA segments as a result of cell signals and sometimes environmental events.
Amplification can occur in vivo (in the living individual) or in vitro (literally 'in glass', or in a plastic vessel in the laboratory).