Neural cell adhesion molecule L1-like protein, also known as close homolog of L1 (CHL1) is the prototypic member of the CTF / NF-1 family of transcription factors that serve as a novel calcium signaling pathway-responsive transcription factor and is considered as a member of the largest ctf complementation group, consisting of 30 of 126 ctf mutants isolated. CHL1 is a cell adhesion molecule highly related to L1. It contains structure plan of six extracellular C2-type immunoglobulin (Ig) domains followed by five fibronectin typeⅢ domains linked by a single membrane-spanning region to a short cytoplasmic domain. The extracellular portion of CHL1 is higyly glycosylated and involved them in hemophilic disease.