Abstract
Contractile forces are implicated in cell polarity and asymmetric division, but their contribution to cell fate is unclear. In this issue of Cell Stem Cell, Shin et al. (2014) show that myosin-II isoforms sense matrix stiffness in hematopoietic stem and progenitor cells, with polarized myosin-IIB promoting asymmetric self-renewal and constitutive myosin-IIA activation promoting cytokine-triggered differentiation.