Stealth sensors: real-time monitoring of the cell cycle

The cell cycle is of key importance to many areas of drug discovery. On the one hand this fundamental process provides the opportunity to discover new targets for anticancer agents and improved chemotherapeutics, but on the other hand drugs and targets in other therapeutic areas must be tested for undesirable effects on the cell cycle. Historically, a wide range of techniques have been developed to study the cell cycle both as a global biochemical process and at the molecular level. This article reviews a range of methods for analysis of the cell cycle and introduces a novel class of dynamic stealth sensors based on expression, localization and degradation of green fluorescent protein under the control of key components of cell cycle regulation. These sensors allow the precise status of the cell cycle to be determined in live cells by fluorescence imaging without perturbing cell cycle progression.