FEM1B is a highly conserved gene, and the protein encoded by FEM1B is a member of the anchorrepeat protein family. Its spatial conformation contains 7 modules in series. FEM1B is involved in the regulation of a variety of biological functions, including apoptosis, protein ubiquitination modification, cell reductive stress and DNA replication stress. FEM1B has been shown to promote apoptosis of tumor cells in colorectal cancer, human T-cell acute lymphoblastic leukemia, and diffuse large B-cell lymphoma, while downregulation of FEM1B inhibits proliferation, invasion, and migration of tumor cells in non-small cell lung cancer. In addition, the structure of FEM1B is related to the HIV regulatory protein Vif. These characteristics of FEM1B may make it a new target for cancer treatment and the regulation of HIV infection.