SLC2A4 and myotonic dystrophy type 2: In a resting muscle cell, the glucose transporter protein GLUT4 is located in vesicles below the plasma membrane and in response to insulin or exercise these GLUT4 vesicles fuse with the plasma membrane to transport glucose from the blood into the cell; a regular exercise program induces an increase in the production of GLUT4 protein through activation of its gene and physical inactivity decreases GLUT4 to levels found in patients with DM2 [28].