FYN, also named as p59-Fyn and SLK, belongs to the protein kinase superfamily, Tyr protein kinase family and SRC subfamily. FYN is implicated in the control of cell growth. It plays a role in the regulation of intracellular calcium levels, with isoform 2 showing the greater ability to mobilize cytoplasmic calcium in comparison to isoform 1. FYN is required in brain development and mature brain function with important roles in the regulation of axon growth, axon guidance, and neurite extension. FYN blocks axon outgrowth and attraction induced by NTN1 by phosphorylating its receptor DDC. This antibody is specific to FYN.