Expression vectors are critical to high efficiency expression of foreign proteins. Thus a vector containing human elongation factor 1α subunit promoter (P_EF-1α) for transcription of genes of interests, and mouse dihydrofolate reductase (dhfr) gene under control of SV40 promoter (P_SV40) for clonal selection and amplification was first constructed . The vector was named pED5. The expression efficiency difference between pED5 and pCdhfr1, a vector utilizing CMV enhancer/promoter (P_CMV-IE) for foreign protein production, was analyzed using human interferon-β (IFN-β) gene and human secreted alkaline phosphatase (SEAP) gene as reporters. When analyzed in transient expression, pED5 showed a little more protein produciton than pCdhfr1. However, in continuous expression, when serum concentration was lessened to slow down cell proliferation, pED5 expressed 3.1 times more reporter proteins than pCdhfr1, which implied that P_EF-1α was less affected by cell cycle status in contrast to P_CMV-IE, making pED5 a good expression vector for foreign protein production.To further enhance protein productivity of expression vectors, two artificial transcription activating domains, AH and VP2, were linked to cI repressor protein of phage λ through a soft linker, respectively, and thus two artificial transcription activators were created. The O_R2-O_R1 sequence of phage λ was inserted into P_EF-1α about 200 bp before TATA box. The artificial transcription activators can bind to O_R2-O_R1 sequence, and are thus conscripted near to the TATA box of P_CMV-IE, activating gene transcription with artificial activating domain AH or VP2. All the components mentioned above were integrated into pED5, producing two vectors: pER-AH and pER-VP2. The two vectors were tested for their efficiency of expressing IFN-β and SEAP reporter genes in comparison with pERFRT, a vector similar to pER-AH and pER-VP2 except for lacking of artificial transcription activators. To abolish transcription efficiency affected by copy number or integration site in chromosome, all the vectors were integrated into FRT site by co-transfecting with an Flp recombinase producing plasmid. The FRT site was pre-inserted into CHO cell chromosome by Invitrogen Corporation. It was showed that pER-AH was only a little more efficient than pERFRT, however, pER-VP2 was 2.7 times more efficient than pERFRT in expressing reporter genes.