Calcium and mitosis

Calcium is thought to be involved in regulating mitotic transitions. The ba sis for this view is set out. Recent data from experiments on sea urchin em bryos is discussed. The relative simplicity of the embryonic cell cycle and the relative ease with which cell physiology can be done in sea urchin emb ryos has allowed the clear demonstration that the phosphoinositide-calcium- calmodulin signalling pathway is required for and regulates mitosis entry a nd anaphase onset. The relevance of the sea urchin work to mitosis in other cell types is briefly discussed.