Flightless 1, originally identified as a Drosophila melanogaster mutant, is a member of the gelsolin superfamily with an N-terminal leucine-rich repeat domain and a C-terminal gelsolin-like domain. Through its bipartite domain structure, Fli-1 can bind to numerous structural and signaling proteins and thus regulate cell migration, wound healing, and inflammation. Furthermore, Fli-1 modulates cell proliferation and survival in cancer cells by interacting with transcription factors such as androgen receptor, estrogen receptor (ER), and carbohydrate responsive element-binding protein.