CLCF1, also known as cardiotrophin-like cytokine factor 1, belongs to the interleukin 6 family of cytokines, which are involved in cell signaling through phosphorylation of gp130. CLCF1 has a sequence of 225- amino acids with a 27-aa signal peptide, a molecular mass of 22 kDa in mature form, and the highest homology to cardiotrophin-1 and ciliary neurotrophic factor.