2A Sequences and Polycistronic Vector Design Figure 6. Analysis of the difference between T2A, E2A and F2A on EGFP expression by cells. (A) Replacing F2A peptide with T2A peptide in a two-gene construct caused a significant increase in mean EGFP expression per positive cell. (B) Replacing E2A with T2A in a two-gene construct caused a significant increase in the mean EGFP expression per positive cell. (C) In a three-gene construct, the expression of EGFP was not altered after replacing either a single single F2A or E2A with T2A. A significant increase in EGFP expression was detected when both F2A and E2A were replaced with T2A. Data presented as mean 6 SEM from 3 independent experiments. AU = arbitrary units. doi:10.1371/journal.pone.0048668.g006 PLOS ONE | www.plosone.org 10 November 2012 | Volume 7 | Issue 11 | e48668