Expression Cassette

**What it means:** In gene therapy, an "expression cassette" is the **complete package of genetic instructions** packed into the viral vector. It's not just the MEF2C gene itself — it also includes: - A **promoter** (the "start here" signal telling cells when to read the gene) - **Enhancers** (the "read louder" signals) - **Polyadenylation signals** (the "stop here" signal) - The **coding sequence** (the actual MEF2C gene instructions) **Analogy:** If the MEF2C gene is a recipe, the expression cassette is the whole cookbook page — the recipe itself plus all the instructions for "cook at 350°F for 30 minutes" and "serve with rice." Without the surrounding elements, the gene alone can't be properly read by cells.