The neural cell adhesion molecule (NCAM) responds to cues in the external environment and transmits signals to the cell through extracellular and intracellular interactions with a number of other signal transduction molecules. One such NCAM interaction partner is the fibroblast growth factor receptor (FGFR). NCAM interacts with FGFR via two fibronectin type III (FN3) modules in the extracellular part of NCAM. These modules consist of beta-strands and connecting loop regions. Based on structural analysis of the NCAM FN3 modules, four peptide sequences, FGL, BCL, dekaCAM, and FRM, encompassing various FN3 module loop regions, have been identified as FGFR ligands. All four peptides activate FGFR and differentially modulate a number of neuronal functions, such as differentiation, survival, and synaptic changes that are important for learning, memory, and neuronal regeneration.