Complex transcriptional interaction between VAX1 and cFOS on the GnRH E/P-luciferase promoter. A–C, E) GN11 (white) and GT1-7 (grey) cells were co-transfected with VAX1, cFOS (horizontal bars), and/or AFOS (vertical bars) and fold change in luciferase expression evaluated on the indicated luciferase reporters. Mutation sites (black bar on schematic over histogram), correspond to the sequences underlined in Figure 1F. Two-way ANOVA followed by Sidak’s post-hoc test * p < 0.05; ** p < 0.01; as compared to control (empty vector). D) Hypothetical model of the role of increased levels of cFOS on VAX1 regulation of the GnRH E/P-luciferase construct. F, G) GN11 and GT1-7 cells were co-transfected with VAX1, SIX6 (200 ng), cFOS (100 ng) or their corresponding empty vectors and fold induction of an ATTA-multimer TK-promoter luciferase reporter evaluated. Two-way ANOVA followed by Sidak’s multiple comparison test, ** < 0.01, *** < 0.001 as compared to empty vector (pcDNA, CMV) or as indicated by bracket, n=3–5.