P3xFlag-CMV-14 expression vector is a 6.3 KB carrier derived from the pCMV5 vector, which is used for transient expression in mammalian cells or the stable expression of C terminal with 3xFlag tag fusion protein. Three adjacent Flag epitopes (Asp-Tyr-Lys-Xaa-Xaa-Asp) were encoded by the downstream fragment of the vector. This makes it possible to detect protein expression using M2 Flag antibody.