Many cells move in and out of a 'quiescent' state, in which they stop dividing. Researchers in France show that the deprivation and addition of glucose triggers yeast cells to enter and exit from this state, respectively, regardless of which stage of the cell cycle they are in. This contradicts the common belief that cells can become quiescent only when they are in a specific phase of the cell cycle.
Isabelle Sagot and her colleagues at the National Centre for Scientific Research in Bordeaux found that Saccharomyces cerevisiae cells in all stages of the cell cycle display the cellular hallmarks of quiescence entry. The authors also found that glucose added to the cells had to be metabolized to a certain point for the cells to exit from quiescence. This suggests that quiescence signals are more closely linked to the cell's metabolic status than to the cell cycle.