NAF1 and pancreatic insulinoma: The findings described above reveal that a reduction in NAF-1 protein level in INS-1E insulinoma cells results in a significant decrease in glucose-stimulated insulin secretion (Figure 1), which was accompanied by structural changes to mitochondria and ER (Figure 2 and Figure 3), as well as a decrease in mitochondrial functions (Figure 4 and Figure 5).