Cardiotrophin-like cytokine factor 1 (CLCF1), also known as Novel Neurotrophin-1 (NNT-1) or B cell-stimulating factor-3 (BSF-3), is a protein that in humans is encoded by the CLCF1 gene.

This gene is a member of the glycoprotein (gp)130 cytokine family and encodes cardiotrophin-like cytokine factor 1 (CLCF1). CLCF1 forms a heterodimer complex with cytokine receptor-like factor 1 (CRLF1). This dimer competes with ciliary neurotrophic factor (CNTF) for binding to the ciliary neurotrophic factor receptor (CNTFR) complex, and activates the Jak-STAT signaling cascade. CLCF1 can be actively secreted from cells by forming a complex with soluble type I CRLF1 or soluble CNTFR. CLCF1 is a potent neurotrophic factor, B-cell stimulatory agent and neuroendocrine modulator of pituitary corticotroph function. Defects in CLCF1 cause cold-induced sweating syndrome 2 (CISS2). This syndrome is characterized by a profuse sweating after exposure to cold as well as congenital physical abnormalities of the head and spine. Alternative splicing results in multiple transcript variants encoding distinct isoforms.[provided by RefSeq, Oct 2009].
Function: Cytokine with B-cell stimulating capability. Binds to and activates the ILST/gp130 receptor.