What is the functional outcome of Netrin-1 binding to its receptor in gut epithelium?

• A. It inhibits cell growth.
• B. It promotes cell growth.
• C. It causes cell death.
• D. It blocks receptor signaling.

Answer: (B)

Netrin-1 binds to its receptors in gut epithelium to promote survival and growth of the cells. When netrin-1 engages receptors like DCC and UNC5, it blocks the pro-apoptotic signaling that occurs when those receptors are unbound and activates downstream pathways (such as PI3K/Akt and MAPK/ERK) that drive cell survival, proliferation, and migration. This helps maintain the intestinal epithelium and supports repair after injury. So the functional outcome is promoting cell growth. The other options don’t fit because binding netrin-1 does not suppress growth, induce death, or block receptor signaling; it actually triggers pro-survival, pro-growth signaling.