TRANCE/OPGL/RANKL/ODF is a recently identified member of tumor necrosis factor family. TRANCE (TNF-related activation-induced cytokine receptor) or RANKL {receptor activator of NF-kB (RANK) ligand} has been implicated in interactions between T cells and dendritic cells (1-2). RANK ligand (RANKL/TRANCE) binds to RANK on dendritic cells, upregulates the expression of anti-apoptotic protein BcL-XL suggesting a role in dendritic cell survival (2). TRANCE/RANKL is also important in T- and B-cell maturation (3). As OPGL/ODF (Osteoprotegerin Ligand/Osteoclast differentiation factor), the same protein can both activate mature osteoclasts and mediate osteoclastogenesis (4,5). OPGL/TRANCE deficient mice show severe osteoporesis and complete absence of osteoclasts as a result of lack of osteogenesis (3).