FIGURE 8.

Experimental confirmation of the systems properties of the MAPK-associated regulatory module. Panel A depicts peak MEK and ERK phosphorylation (10 min of stimulation with anti-IgG) levels obtained as a function of changes either in MKP3 or PP2A concentrations as described in the text. For the profiles obtained in silico (Predicted), the concentration ranges utilized is described in supplemental Fig. S8, whereas the extent of variation in phosphatase concentration/activity obtained experimentally (Experimental) is described under “Experimental Support for Signal Processing Function of Phosphatase Cascade.” The anti-IgG concentrations employed for the experiment in high ligand dose (upper panel) were 10 (blue line) and 25 (red line) μg/ml, whereas for low ligand dose (lower panel), it was 0.05 (blue line) and 0.5 (red line) μg/ml. OA, okadaic acid. Panel B describes the effects of combined variations in levels/activities of both MKP3 and PP2A on the magnitude of ERK phosphorylation. Here again, a comparison between the in silico (Predicted) and the experimentally (Experimental) obtained results is shown. Although a similarity in profiles between the two groups is clearly evident, the absence of a higher degree of concordance was primarily due to the limited number of data points in the experimental group. As described in the text, MKP3 levels were varied in the experimental sets either through specific depletion by siRNA (KD) or by overexpression (OE).