Fibroblast growth factor 13 (FGF13), a member of the FGF11 subfamily, is a kind of intracrine protein similar to other family members including FGF11, FGF12, and FGF14. Unlike classical FGF, FGF13 exerts its bioactivities independent of fibroblast growth factor receptors (FGFRs). FGF13, a nonsecretory protein of the FGF family, is expressed in cerebral cortical neurons during development and is a candidate gene for syndromal and nonspecific forms of X-chromosome-linked mental retardation. The FGF-13 regulates glioma cell invasion and is important for bevacizumab-induced glioma invasion. FGF-13 plays a crucial role in neuron polarization and migration in the cerebral cortex. In mouse FGF-13 RNA was detected in developing central nervous system in cells, and was also found throughout the peripheral nervous system.