Expression of HSA gene on different vectors in COS-7 cells. COS-7 cells were transfected with HSA vectors using Lipofectamine 2000, cultured for 48 h, harvested and applied to Western blot. Control (C) cells treated the same way without DNA. (A) HSA vectors: pcDNA3.1/GS (G1), pcDNA3.1/V5-His (H1), pcDNA3.1/V5-His with intron A (H2), gWIZ (W1) and gWIZ with Kozak (W2). (B) HSA vectors:VR1012 (V1) and VR1012 with Kozak (V2). The vectors were tested at least three times.