Which statement is a correct example of the endocrine system releasing hormones that are used by target cells in the body? The ovaries release estrogen to support reproduction. Estrogen is a steroid hormone, so it binds with a protein to become a lipoprotein. It is then transported by the blood to target cells. The thyroid releases TSH (thyroid-stimulating hormone), which is a steroid hormone, and it must bind with a protein to become a lipoprotein to be transported by the blood to target cells. The testes release testosterone to support reproduction. Testosterone is a nonsteroid hormone, so it binds with a protein to become a lipoprotein. It is then transported by the blood to target cells. The thyroid releases T4 (thyroid hormone, thyroxine), which is a nonsteroid hormone, and it must bind with a protein to become a lipoprotein to be transported by the blood to target cells.