x1 = HR
x2 = G
x3 = ERK
x4 = PIP2
x5 = DAG
x6 = PKC
x7 = PKC_a
x8 = GpERK
x9 = bpERK
x10 = barr1
x11 = barr2
x12 = G_a
x13 = HRP1
x14 = Hbarr1RP1
x15 = Hbarr2RP1
x16 = HRP2
x17 = HRbarr2
x18 = Hbarr2RP2
x19 = GRK2_3
x20 = GRK5_6
x21 = pERK