Both GLUT4 and the insulin-regulated aminopeptidase (IRAP) (a protein which displays a similar insulin-stimulated translocation to the plasma membrane as GLUT4) are redistributed to higher density intracellular membrane fractions in T2DM and do not translocate to the cell surface in response to insulin (Garvey et al., 1998; Maianu et al., 2001). This evidence concerns the gene INS and type 2 diabetes mellitus.