x1 = Rb
x2 = pRb
x3 = E2f
x4 = RbE2f
x5 = E1
x6 = C1
x7 = pC1
x8 = E1C1
x9 = P21
x10 = Ce
x11 = Ca
x12 = CeP21
x13 = CaP21
x14 = aPcna
x15 = iPcna
x16 = Rc
x17 = pRc
x18 = aRc
x19 = iRc
x20 = Dna
x21 = P53
x22 = Dam
x23 = Pr
x24 = tRb
x25 = tE2f
x26 = tE1
x27 = tC1
x28 = tCe
x29 = tCa
x30 = tP21