Interleukin-11 (IL-11) is encoded by the II11 gene. IL-11 is a multifunctional cytokine first isolated from bone marrow-derived stromal cells. IL-11 receptor activation requires formation of a complex of two IL-11 molecules with two molecules of the ligand-binding IL-11 Rα subunit and two molecules of the expressed cell signaling β subunit, gp130. IL-11 is a member of the IL-6 superfamily, distinguished based on their use of the common co-receptor gp130. IL-11 can directly stimulate the proliferation of hematopoietic stem cells and megakaryocyte progenitor cells, and induce megakaryocyte maturation resulting in increased platelet production. Mature murine IL-11 shares 88 % amino acid sequence identity with human IL-11.