INS and diabetes mellitus: In addition, due to the overexpression of the furin-cleavable human insulin (INS-FUR) gene (a modified form of human proinsulin, which permits cleavage into mature insulin via furin enzymes in nonpancreatic cells), these cells were capable of synthesizing, storing, and secreting mature human insulin in a glucose-responsive manner and reversed diabetes upon transplantation in STZ-diabetic NOD/Scid mice [18].