What is the primary function of epidermal growth factor (EGF)?

• A. To produce sebum for skin lubrication.
• B. To stimulate cell reproduction and healing.
• C. To enhance fiber growth.
• D. To protect against UV radiation.

Answer: (B)

The primary function of epidermal growth factor (EGF) is to stimulate cell reproduction and healing. EGF is a potent mitogen for a wide variety of cell types, but it is especially influential in the epidermis, where it promotes the proliferation of keratinocytes. This is crucial for maintaining the skin's integrity and facilitating the healing process following injuries or damage. EGF also plays a role in wound healing by promoting the formation of new cells, which is important for the repair of skin tissues.

The other functions mentioned in the options do not relate to the main role of EGF. While lubrication of the skin is primarily the function of sebum, fiber growth is typically associated with growth factors such as fibroblast growth factor (FGF), and protection against UV radiation is mainly the function of melanin and other protective mechanisms in the skin. Thus, the focus of EGF's activity on stimulating cell growth and repair makes it an essential factor in skin physiology.