Cover image

The cell cycle, G1 phase specifically, is a sensitive period during which cell fate decisions are made. In this issue, a study describes in-depth analysis of single-cell RNA-seq profiles of young and old mouse hematopoietic stem and progenitor cells, which revealed age-dependent differences in cell cycle and differentiation signatures. The cover depicts a mouse riding a bicycle on a single-cell path, where each wheel represents a type of cell cycle and its possible outcome. A cell cycle with a short G1 phase (black) is associated with a self-renewal-biased transcriptional signature, whereas a cell cycle with a long G1 phase (yellow) is associated with differentiation. Hematopoietic stem and progenitor cells are located in the bone marrow, which is represented by the bone (lower left). (Cover illustration by Anna Hupalowska, www.annahupalowska.com. [For details, see Kowalczyk et al., pp. 1860–1872.])