Molecular model of colchicine drug (mostly green, upper centre) complexed with free alpha or beta tubulin dimers (cream and purple). Tubulin is a protein that polymerises to form microtubules. Microtubules are a part of a cell's cytoskeleton. Binding of colchicine prevents the tubulin dimers from polymerising and stops microtubule extension. Microtubules play an important role in inflammatory pathways in the body, so this inhibits these pathways. Colchicine is used to treat gout and familial Mediterranean fever.