x1 = Auxin
x2 = X
x3 = PLSp
x4 = Ra
x5 = Ra_star
x6 = RaT
x7 = CK
x8 = ET
x9 = PLSm
x10 = Re
x11 = ReT
x12 = Re_star
x13 = CTR1
x14 = CTR1T
x15 = CTR1_star
x16 = IAA
x17 = ACC
x18 = CK_ex