Table 1.

Key features of the mammalian cell cycle that could be exploited to alter cell fate

	Conventional mammalian cell cycle (hours) [7]	Ultrafast cell cycle (hours) [8••]	Key molecular events	Events relevant for cell fate determination
G1	11	~1	Cell growth (increase in size) Restriction point active	Reorganizing chromatin after mitosis leading to potential changes in effective concentration and/or compartmentalization of transcription factors [9•, 10••, 11•]
S	8	6	Genome replication	Replicating epigenetic information such as DNA methylation and histone patterns [2–5, 12]
G2	4	~0.5	Cell growth (increase in size) Mitotic checkpoint active	Preparing chromatin for mitosis leading to potential changes in effective concentration and/or compartmentalization of transcription factors
M	1	~0.5	Cytokinesis	Cessation of transcription while key transcription factors remain bound to chromatin to mark active transcription sites in the next cycle [6]

The dramatic cell fate change seen with Yamanaka reprogramming is accompanied with a greatly accelerated cell cycle