0 -> pRB
pRB -> pRBp
pRBp -> pRB
pRB -> 0
0 -> E2F1
E2F1 -> 0
0 -> CycDi
CycDa -> CycDi
CycDi -> CycDa
CycDi -> 0
CycDa -> 0
0 -> AP1
AP1 -> 0
pRBp -> pRBpp
pRBpp -> pRBp
pRBpp -> 0
pRBp -> 0
0 -> CycEi
CycEi -> CycEa
CycEa -> CycEi
CycEi -> 0
CycEa -> 0