Cellular Basics

Cell Responses

How do cells respond to steroid hormones?

Progesterone, estrogen, testosterone, and glucocorticoids are naturally occurring steroid hormones that “signal” molecules. After entering a target cell, the steroid hormone binds to a receptor protein and starts a cascade of events that ultimately activates (“turns on”) or inhibits (“turns off”) a specific set of genes. (For more about anabolic steroids and humans, see the chapter “Physiology: Animal Function and Reproduction.”)

