摘要 |
<p>Nucleic acid molecules comprising at least a first signal site and a recombinase gene operably linked to an expression control sequence, such that upon entry into a cell, there is a first signal site and a second signal site positioned to mediate excision of a sufficient portion of either the recombinase gene or the expression control sequence to extinguish recombinase activity when the first and second signal sites are contacted with a recombinase, cells, transgenics and uses of the foregoing.</p> |