The Caulobacter cell cycle exhibits time-dependent expression of differentiation events. These include the morphological transition of a swarmer cell to a replication-competent stalked cell and the subsequent polarized distribution of specific gene products that results in an asymmetric predivisional cell. Cell division then yields a new swarmer cell and a stem-cell-like stalked cell. Two-component signal transduction proteins involved in cell cycle control and proteins required for cell division and flagellar biogenesis have been shown to be regulated temporally and spatially during the cell cycle. The mechanisms underlying this regulation include protein phosphorylation and proteolysis.