Generally, mutagenesis of dna by the insertion of one or more bases. Specific examples:
1. Oncogenesis by insertion of a retrovirus adjacent to a cellular proto-oncogene.
2. A strategy of mutagenesis with transposons. After a round of transposition, progeny are screened by pcr, with transposon and gene specific primers, for the proximity of the transposon sequence to the gene of interest. As pcr can only produce products up to 1-2 kb, a large fraction of progeny identified as positive by pcr will have a transposon close enough to the gene to inactivate or otherwise alter its pattern of expression.