Final answer:
Platelet-derived growth factor functions in paracrine signaling, targeting nearby cells to stimulate processes such as cell division and tissue repair.
Step-by-step explanation:
Growth factors such as platelet-derived growth factor primarily function in paracrine signaling. This type of signaling occurs between cells that are in close proximity to each other. Paracrine signals are especially important in regulating processes such as cell division, where they act locally by diffusing through the extracellular matrix and elicit quick responses that are usually of short duration.
In the case of platelet-derived growth factor, it is involved with healing and tissue repair by signaling nearby cells to grow and divide. This mechanism ensures that growth factors effectively stimulate target cells in their vicinity, which is critical for a coordinated response during processes like wound healing.