Licensing factors Lichen Mutualistic association of a fungus with a green alga or a cyanobacterium . A molecule that binds to another molecule or to a cell. Lignin Complex substance found in the cell walls of sclerenchyma and xylem tissue, which are strengthened by it. The cavity inside a tubular structure such as a blood vessel or kidney tubule. Most of the interleukins are lymphokines.
Lymphokines represent a subset of cytokines .
Lymphoma A cancer of lymphoid tissue. Lymphotoxin Cytokine that triggers apoptosis. The disintegration of a cell following damage to its plasma membrane.