Fig. 6. Effect of Syt V and Syt IX overexpression on insulin exocytosis. INS-1E cells were transiently cotransfected with a plasmid encoding human growth hormone (hGH) and 1 µg of the control pcDNA3 (control), the Syt V or the Syt IX vectors. Two days later, the cells were incubated in the presence of 2.5 mM glucose (open bars) or with 15 mM glucose (filled bars) for 30 minutes. The cells were then collected and the expression of the exogenous proteins was analysed by western blotting using anti-Syt V or anti-Syt IX antibodies (top panels). The same membranes were also blotted with an anti-myc antibody. The positions of endogenous Syt V and Syt IX and their transfected myc-tagged counterparts (loaded on duplicates) are indicated by the arrows. After incubation the amount of hGH secreted by the cells was measured by ELISA. The lower panel shows the mean+s.e.m. of three independent experiments performed in triplicate.