| Receptor activator of NF kappaB ligand ( RANKL ) activates TAK 1 mitogen activated protein kinase kinase kinase through a signaling complex containing RANK , TAB 2 , and TRAF 6 . ^^^ Here , we demonstrate that TAK 1 and TAB 2 participate in the RANK signaling pathway . ^^^ Dominant negative forms of TAK 1 and TAB 2 inhibit NF kappaB activation induced by overexpression of RANK . ^^^ In 293 cells stably transfected with full length RANK , RANKL stimulation facilitates the formation of a complex containing RANK , TRAF 6 , TAB 2 , and TAK 1 , leading to the activation of TAK 1 . ^^^ |