Cell cycle control: many ways to skin a cat

Thirty exponential cell divisions after fertilization would produce the number of cells in a baby mouse, but would not make a mouse. Sophisticated controls govern the cell cycle during development. These controls appear to play a central role in sculpting biological form. Rapid advances in our understanding of the machinery that drives the cell cycle provide a foundation for investigation of the molecular nature of cell cycle control in development. In this article, I emphasize that the design of the cell cycle machinery provides numerous inputs for regulation. I hope that the emphasis I have chosen will avert a tendency towards a narrow perception of cell cycle control.