Sustained oscillations in S1 and S2 as function of signal dose. Strength of the signal activating the MAPK cascade ‘Sig’ was varied and the range of ‘Sig’ in which both S1 and S2 would exhibit oscillations was studied. (A) After a certain threshold value of ‘Sig’, increase in ‘Sig’ resulted in decrease in the frequency of MK** oscillations in S1, whereas the maximum amplitude of oscillations remained unaltered. When the range of ‘Sig’ triggering such oscillations was crossed beyond 50nM, the oscillations ceased to exist (data not shown). (B) In S2, beyond a threshold value of Sig (~ 5 Nm) required to trigger oscillations, almost any value of ‘Sig’ triggered oscillations with conserved frequency and amplitude.