Figure 4.

Pattern transition of actin assembly. A bird’s-eye view of the various actin assemblies. The assembly pattern of the actin core evolves from a cluster, to a ring, to a belt in invadopodia in RSV-BHK cells [28] and in osteoclasts on glass [21]. In osteoclasts on apatite–collagen-coated glass [24] and on dentin [38], a ring-like sealing zone evolves from the uncharacterized actin patch. Most crescent-like sealing zones (80%) on bone evolve from a ring-shaped sealing zone, whereas a small number of them (20%) directly develops from the actin patch [15]. In Dictyostelium cells, the actin wave takes various patterns including a circular ring, an arc shape, and a belt [39]. The actin wave originates from the actin clusters embedded in a PtdIns(3,4,5)P3 patch. The wave does not contain the actin core.