Figure 2. Inhibition of c-Abl promotes insulin production by β cells in resting state.

NIT-1 cells were cultured in low glucose DMEM medium (glucose 4.5 mM) for a few days. A. The NIT-1 cells were harvested and then cultured in low glucose DMEM medium with different conditions: Imatinib 0 µM, 0.3 µM, 1 µM or 3 µM for 6 hrs. The supernatants from all cultures were harvested and measured for insulin production by ELISA. The results presented were from a representative of three independent experiments. Two-way ANOVA with Bonferroni post-test was performed. B. The NIT-1 cells were cultured in low glucose DMEM medium with Imatinib 0 µM, 0.3 µM or 1 µM for 6 hrs. The insulin gene expression was examined by real-time RT-PCR. The levels of insulin gene expression were normalized relative to β actin. The experiments were repeated 3 times with reproducible results. Two-way ANOVA with Bonferroni post-test was performed. C. NIT-1 cells were transfected with c-Abl siRNA or control siRNA for 24 hrs. Then the transfected cells were cultured in low glucose DMEM medium for 6 hrs. An additional group was also included by culturing c-Abl siRNA transfected NIT-1 cells with 1 µM Imatinib. The supernatants were harvested from the above cultures and the insulin concentration was examined by ELISA. One-way ANOVA with post hoc test was performed. Similar results were obtained from at least 3 independent experiments. *: p<0.05, **:p<0.01,***:p<0.001.