An effector is a protein, often an enzyme, within a hormonally stimulated cell that helps produce the end result of the hormonal stimulation. Known effectors include transcription factors involved with altering cellular gene transcription, enzymes controlling the storage and retrieval of intracellular glucose, enzymes that produce steroid hormones, and intracellular structural proteins that control cellular shape and movement. These molecules often use intracellular energy stores and result in the amplification of hormonal signals, so that binding of a few hormone molecules can make cells do things that would otherwise be impossible, if they only depended on the energy from binding the hormone molecules, themselves.