Two different hormones, T3 and hCG, both make a key protein (StAR) in mouse testicle cells work harder to produce steroids, and when you use both together, they boost it even more — like two different keys that each unlock the same door, and using both at once opens it wider.

A hormone called T3 makes normal mouse testicle cells produce more testosterone, which means it doesn’t just work in cancer cells—it also works in healthy ones.

A thyroid hormone called T3 turns up a gene called SF-1 in mouse testicle cells, and without SF-1, T3 can’t make the cells produce sex hormones—so SF-1 is like a middleman helping the hormone do its job.