The integrity of cell–cell junctions is essential for the stability and contractility of epithelial cells and tissues. Junction formation involves the tethering of an actin filament to a minimal E-cadherin complex, followed by the recruitment of α-actinin and vinculin. Junction assembly is known to require tension, but it is unclear how the force is propagated to the nascent junction. In this study, Nivetha Kannan and Vivian Tang (Kannan and Tang, 2018) now further investigate tension generation at E-cadherin by using live-imaging of venus-α-actinin. They show that endogenous cellular contraction is associated with the accumulation of α-actinin-4 at the cell junction over time and involves an inward movement of the lateral plasma membrane. This movement is mediated by the membrane-associated motor myosin-1c (myo-1c), as its knockdown compromised membrane integrity and prevented the force-dependent recruitment of α-actinin-4. In addition, myo-1c-depleted cells also showed constant blebbing, suggesting that myo-1c is necessary for the coupling between the lateral membrane and the actin cytoskeleton. Interestingly, application of external forces to a mature monolayer of myo-1-knockdown cells was able to restore α-actinin-4 localisation to the junctions, indicating that the dependency of α-actinin-4 on myo-1c is indirect and strictly due to the force transmission function of myo-1c. This work thus establishes an important role for myo-1c in tension generation and force transmission at the lateral cell–cell junction.