Final answer:
The insertion of GLUT4 in the muscle cell membrane, facilitated by the action of insulin, increases glucose uptake into the cell for energy use or storage as glycogen.
Step-by-step explanation:
The insertion of GLUT4, a glucose transporter, in the muscle cell membrane increases cellular glucose uptake. This process is initiated by the hormone insulin, which is released from the pancreas when blood glucose levels rise. Insulin activates the insulin receptor, a tyrosine kinase receptor, leading to a cascade of biochemical reactions that promote the movement of GLUT4-containing vesicles to fuse with the plasma membrane. Consequently, this increases the uptake of glucose via facilitated diffusion into the muscle cells, where it can be used for energy or stored as glycogen.