This poster was presented at ESACT meeting in 2017 in Lausanne, Switzerland. Cell line development for production of monoclonal antibody therapeutics requires an expression vector encoding both the heavy and light chains of the antibody. When expression of the heavy and lights chains is driven by the same promoter, the sequence redundancy can be problematic for verifying the vector sequence, copy number and insertion site in the host cell genome. This poster describes the work done to identify an expression vector that maintains a high level of antibody expression but lacks the sequence similarities, easing the cell line development workflow.