Gene transduction of luciferase from murine retroviral based vectors. Schematic of the panel of MLV based vectors expressing luciferase and their transduction activity. Effects of CTE and WPRE elements on the gene transfer of luciferase within a CPIL backbone. LTR, long terminal repeat; ψ, RNA packaging region; SD, splice donor; SA, splice acceptor. RLU, relative light units of luciferse activity. Assays were performed in triplicate and the results are shown as mean ± standard deviation. P-values from one tailed student t-tests (N = 3); comparing CPILW individually to CPIL, CPWIL, CPCIL or CPILC were all p < 0.001.