Cardiotrophin-1 is a novel member of the interleukin-6 cytokine family. Mouse CT-1 mRNA is about 1.4 kb in length, and the encoded protein contains a 203-aa open reading frame. It utilizes gp130 and LIFR as the signal transducing receptor components. As a multifunctional cytokine, it induces cardiac myocyte hypertrophy and promote cardiac myocyte survival. It can induce a phenotypic switch in rat sympathetic neurons and promote the survival of dopaminergic neurons, ciliary neurons and motoneurons. It can also inhibit the growth of the mouse myeloid leukemia cell M1, and induce liver acute phase response. The chronic administration of CT-1 to mouse increases platelet counts, red blood cell counts and haemoglobin concentration.