Schematic of the proposed mechanism for PD-L1 regulation of rear contraction during persistent cell migration. PD-L1 regulates cell polarity by maintaining lower membrane tension at the cell rear compared with the leading edge of migrating cells. Consequently, caveolae form at the rear where PD-L1 associates with the β4 integrin. This association enables the β4 integrin to associate with F-actin and activate RhoA-mediated contractility that increases actomyosin tension. This process causes rear retraction that results in the formation of PD-L1 and β4 integrin containing retraction fibers and migrasomes. The graph is created with BioRender.com.