TIMP1 is an extracellular inhibitor of MMPs (see above) including MMP1, 2, 3, 7, 8, 9, 10, 11, 12, 13, and 16. It belongs to the I35 (TIMP) family of irreversible protease inhibitors that function as key modulators of extracellular matrix degradation during tissue development and remodeling. TIMP1 can also act through an MMP-independent mechanism to promote erythropoiesis by stimulating proliferation and differentiation of erythroid progenitors. Recombinant human TIMP-1 is a 20.6 kDa protein containing 184 amino acid residues.