Telephone: +49 241 8085248Running head: LSP1-myosin1e complex regulates cell migration. Abstract Several cytoskeleton-associated proteins and signalling pathways work in concert to regulate actin cytoskeleton remodelling, cell adhesion and migration. We have recently demonstrated that the bi-molecular complex between the leukocyte-specific protein 1 (LSP1) and myosin1e controls actin cytoskeleton remodelling during phagocytosis. In this study, we show that LSP1 down regulation severely impairs cell migration, lamellipodia formation and focal adhesion dynamics in macrophages.Inhibition of the interaction between LSP1 and myosin1e also impairs these processes resulting in poorly motile cells, which are characterised by few and small lamellipodia.Furthermore, cells in which LSP1-myosin1e interaction is inhibited are typically associated with inefficient focal adhesion turnover. Collectively, our findings show that the LSP1-myosin1e bimolecular complex plays a pivotal role in the regulation of actin cytoskeleton remodelling and focal adhesion dynamics required for cell migration.