FMNL1, activated by binding to GTP-bound RAC1, binds actin-associated profilins PFN1 and PFN2 through the proline-rich FH1 domain of FMNL1 (Yayoshi-Yamamoto et al. 2000). The interaction with actin is achieved through the FH2 domain of FMNL1 (Romero et al. 2004, Kovar et al. 2006, Kuhn and Geyer 2014). FMNL1 and profilin-mediated reorganization of actin cytoskeleton is involved in the formation of lamellipodia, which regulates the motility of macrophages (Yayoshi-Yamamoto et al. 2000). FMNL1 was shown to regulate the structure of the Golgi complex, where different transcriptional isoforms of FMNL1 may play different roles (Colon-Franco et al. 2011).