The Golgi apparatus is a stack of membrane-bound, flattened compartments called cisternae . Each cisterna contains a different set of enzymes, making each Golgi compartment distinct. The tightly packed cisternae are held together by Golgi matrix proteins. Tubular Golgi matrix or GM proteins and Golgi reassembly stacking proteins or GRASPs connect adjacent cisternae, providing structural integrity to the Golgi stack. Other matrix proteins called golgins form long chains extending 100 to 400 nanometers from the surface of the Golgi stack to help tether incoming vesicles. During cell division, GM proteins are phosphorylated by mitotic protein kinases causing the Golgi to fragment and disperse throughout the cytosol. When the cell divides, the fragments are evenly distributed in the daughter cells. Once the GM proteins are dephosphorylated by protein phosphatases, they reassemble the Golgi fragments into Golgi stacks.