After a lox2272 site was added in front of the bovine - casein gene 5 ' regulatory fragment , a mammary gland universal expression vector plbcas - hsa - lgl was created 最后在-酪蛋白基因5 `端調(diào)控序列前面,連上一個(gè)lox2272位點(diǎn),最終的乳腺特異性表達(dá)載體plbcas - hsa - lgl構(gòu)建完成。