Binds actin monomers (G actin) and plays a role in multiple processes including the regulation of actin cytoskeleton dynamics, actin stress fibers formation, cell motility and survival, formation of tubules by endothelial cells, and regulation of PPP1CA activity (PubMed:21798305, PubMed:21939755). Involved in the regulation of cortical neuron migration and dendrite arborization (By similarity). {ECO:0000250|UniProtKB:Q2M3X8, ECO:0000269|PubMed:21798305, ECO:0000269|PubMed:21939755}. This is the function of PHACTR1 (phosphatase and actin regulator 1, ENSG00000112137).