The G1/S Transition in Mammalian Stem Cells In Vivo Is Autonomously Regulated by Cell Size

This study investigates how cell size and division are coordinated in multicellular tissues by tracking single epidermal stem cells in adult mice. It reveals that a cell-autonomous size control mechanism, reliant on the RB pathway, determines the timing of S phase entry based on the cell's size. While cell-extrinsic factors influence growth rates, they do not affect this autonomous coupling. The findings challenge existing models of cell cycle regulation in complex tissues and highlight the importance of cell-autonomous size control in regulating cell divisions and contributing to stem cell heterogeneity.