A new method for simultaneously visualizing all four cell cycle phases in living cells using a new fluorescent protein is described in a paper published online this week in Nature Methods. The technology enables improved characterization of the cell cycle and its regulation and can thus enhance our understanding of developmental biology and cancer formation.

Cells cycle between stages of rest, growth, DNA replication, and division. Until recently it was challenging to distinguish between these four stages because it is technically difficult to image signals from many different reporter proteins at once. To overcome this limitation, Michael Lin and colleagues developed mMaroon1, a fluorescent protein at the far-red end of the visible light spectrum that can be imaged simultaneously with turquoise, green, and orange fluorescent proteins. The authors used this far-red reporter to label a protein that marked the transition between the S (DNA replication) and G2 (growth) phases of the cell cycle, making all four stages distinct, whereas previous systems could only distinguish three of the four phases.

Understanding the proper regulation of the cell cycle is essential for understanding normal biological functions; understanding problems with cell cycle regulation can lead to important insights into why some cells become cancerous, and this knowledge may lead to future therapeutic advances.