Interleukin-11 (IL-11) is a member of the IL-6 family of cytokines. IL-11 activates its target cells via binding to the IL-11 receptor (IL-11R), which also exists in soluble forms generated by proteolytic cleavage (sIL-11R, required for trans-signaling). Formation of the IL-11/IL-11R complex leads to the recruitment and homodimerization of two molecules of the signal-transducing β-receptor gp130, which then activates intracellular signaling cascades, including the Jak/STAT, PI3K and ERK pathways.