The nucleus, like other smaller organelles in the cell, is dynamic and can move about in the cytoplasm. In some cells, nuclear movements are concerned with mitosis or meiosis; in others, they are concerned with orienting nuclear divisions; and in still others, they deal with distributing nuclei through the cytoplasm. Recent interest in nuclear positioning has shown that nuclear movements are often mediated by the interactions of dynein and other proteins at the plus ends of astral microtubules with the cell cortex. How the microtubule minus ends interact with the nucleus also affects nuclear movements.