During seed germination, the plant embryo produces the hormone gibberellin which triggers the aleurone cells to release α-amylase for the hydrolysis of starch, proteases, and storage proteins into the endosperm. Evidence that G-proteins play a role in the gibberellin signaling events has been obtained. The breakdown of the starchy endosperm supplies sugars to drive the growth of roots and the acrospire. This release of amylase is considered to be the most important and sole function of the aleurone layer. This effect is inhibited by the plant hormone abscisic acid, which keeps the seed dormant. After completing this function, the aleurone cells in the developing seed undergo apoptosis.