Cyclin G2 may play a role in growth regulation and in negative regulation of cell cycle progesssion. Cyclin G2 expression levels increase through the cell cycle to peak in the mid/late-S phase and decrease during G2/M phase. It may also contribute in maintaining the quiescent state of differentiated cells. Cyclin G2 is similar to cyclin A in the cyclin box, although no kinase activity is detected.