Molecular motor proteins are crucial for the proper distribution of organelles and vesicles in cells. Much of our current understanding of how motors function stems from studies of single motors moving cargos in vitro. More recently, however, there has been mounting evidence that the cooperation of multiple motors in moving cargos and the regulation of motor–filament affinity could be key mechanisms that cells utilize to regulate cargo transport. Here, we review these recent advances and present a picture of how the different mechanisms of regulating the number of motors moving a cargo could facilitate cellular functions.
