**Core Concept**
Insulin is a hormone produced by the pancreas that plays a crucial role in regulating blood glucose levels. It facilitates glucose uptake in cells, inhibits glucose production in the liver, and promotes the storage of glycogen.

**Why the Correct Answer is Right**
Insulin stimulates glucose uptake in cells by activating the insulin receptor, which triggers a cascade of signaling pathways that lead to the translocation of glucose transporter 4 (GLUT4) to the cell surface. This allows glucose to enter the cell, thereby lowering blood glucose levels. Insulin also inhibits glucose production in the liver by suppressing the expression of key enzymes involved in gluconeogenesis, such as phosphoenolpyruvate carboxykinase (PEPCK). Additionally, insulin promotes the storage of glycogen by activating glycogen synthase, which catalyzes the formation of glycogen from glucose.

**Why Each Wrong Option is Incorrect**
**Option A:** This action is actually a function of insulin, as it promotes the storage of glycogen.

**Option B:** This action is also a function of insulin, as it inhibits glucose production in the liver.

**Option C:** This action is NOT a function of insulin, as glucagon is a hormone produced by the pancreas that raises blood glucose levels by stimulating glucose production in the liver and glycogenolysis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that insulin stimulates the uptake of glucose in cells, whereas glucagon promotes the release of glucose from stored glycogen, highlighting the opposing roles of these two hormones in glucose metabolism.

**Correct Answer: C. Glucagon promotes the release of glucose from stored glycogen.**