Ca(2+)-dependent actin filament-severing protein that has a regulatory function in exocytosis by affecting the organization of the microfilament network underneath the plasma membrane (PubMed:9671468). Severing activity is inhibited by phosphatidylinositol 4,5-bis-phosphate (PIP2) (By similarity). In vitro, also has barbed end capping and nucleating activities in the presence of Ca(2+) (PubMed:9671468). Required for megakaryocyte differentiation, maturation, polyploidization and apoptosis with the release of platelet-like particles (By similarity). Plays a role in osteoclastogenesis (OCG) and actin cytoskeletal organization in osteoclasts (PubMed:25275604, PubMed:25681458). Regulates chondrocyte proliferation and differentiation (By similarity). Inhibits cell proliferation and tumorigenesis. Signaling is mediated by MAPK, p38 and JNK pathways (By similarity). Fails to nucleate actin polymerization, although it severs and caps actin filaments in a Ca(2+)-dependent manner. Ubiquitous. Highly expressed in mature osteoclasts (at protein level) (PubMed:25275604). Isoform 2 is expressed in blood cells (PubMed:9671468). Expression is induced during osteoclastogenesis. Knockdown in bone marrow monocytes protect mice from bone resorption in periodontal disease model. Belongs to the villin/gelsolin family.