A short G1 phase is an intrinsic determinant of naïve embryonic stem cell pluripotency

► We engineered mouse ES cells for live cell imaging of cell cycle progression. ► mESCs in the G1 phase have an increased susceptibility to differentiation. ► G1 phase duration varies according to the pluripotency state. ► LIF regulates the kinetics of G1 phase progression in naïve ES cells.