May act as a link between RND2 signaling and regulation of the actin cytoskeleton (By similarity). Required to coordinate membrane tubulation with reorganization of the actin cytoskeleton during the late stage of clathrin-mediated endocytosis. Binds to lipids such as phosphatidylinositol 4,5-bisphosphate and phosphatidylserine and promotes membrane invagination and the formation of tubules. Also enhances actin polymerization via the recruitment of WASL/N-WASP, which in turn activates the Arp2/3 complex. Actin polymerization may promote the fission of membrane tubules to form endocytic vesicles. May be required for the lysosomal retention of FASLG/FASL. {ECO:0000250, ECO:0000269|PubMed:15252009, ECO:0000269|PubMed:16318909, ECO:0000269|PubMed:16326391, ECO:0000269|PubMed:16418535, ECO:0000269|PubMed:17512409}. This is the function of FNBP1 (formin binding protein 1, Ensembl gene identifier ENSG00000187239).