Cells can spontaneously change shape even without external signals, but the underlying mechanisms behind this form of self-organization have remained unclear. Now, researchers from Japan have discovered self-propelled treadmilling actin filaments (SpTAs), mobile protein assemblies that function as s elf-propelled particles. The team's work shows that even though SpTAs move randomly, they push the cell membrane outward to grow protrusions, thereby defining the overall shape of the cell. The work appears in EMBO Reports. ...read more read less