Using recombination techniques, the gene fragment CED-9, derived from pBS, was incorporated into pGEM-7zf(+) and formed a new vector pGEM-ced9, in order to get the right endonuclease sites.

• 从质粒pBS中获取CED-9基因片段，构建中间载体pGEM-ced9以获得合适的酶切位点。