Final answer:
GLUT4 is not a primary active transport pump because it does not require ATP to move glucose into cells; it operates via facilitated diffusion, unlike the sodium/potassium, calcium, and proton pumps which do require ATP.
Step-by-step explanation:
Among the options listed, GLUT4 is NOT a primary active transport pump. Primary active transport requires energy from ATP to move ions or molecules across a membrane against their concentration gradient. Examples include the sodium/potassium pump (sodium out of the cell and potassium into the cell), the calcium pump (calcium ions out of the cell), and the proton pump (hydrogen ions out of the cell). These pumps typically move substances from areas of lower concentration to higher concentration, using carrier proteins that change shape to carry ions or molecules across the membrane.
On the other hand, GLUT4 is a transporter that facilitates the passive movement of glucose into cells via a mechanism known as facilitated diffusion, which does not require ATP and is therefore not considered a form of primary active transport.