Taking the A-train: actin-based force generators and organelle targeting.

The actin-driven process of cytoplasmic streaming in plant cells is widely believed to be the earliest documented example of cytoskeleton-driven organelle movement. In the decades since these seminal findings, two mechanisms of actin-based intracellular movement have been identified in multiple cell types: one is myosin dependent and the other is dependent upon the Arp2/3 complex for actin nucleation and polymerization. Here, we describe mechanisms of force generation and directed movement that use the actin cytoskeleton, as well as those that target actin-dependent force generators to different subcellular compartments.