| We report the isolation of RYBP , a recently identified member of the mammalian polycomb complex , as an E2F6 interacting protein . ^^^ Mapping studies indicate that RYBP binds within the known `` repression domain ' ' of E2F6 . ^^^ Moreover , we demonstrate that endogenous E2F6 and polycomb group proteins , including RYBP , Ring 1 , MEL 18 , mph 1 , and the oncoprotein Bmi 1 , associate with one another . ^^^ |