IFNγ-induced STAT1 pathway activation: Experimental time series and computational simulation results. Experimental data: DSL-6A/C1 cells were stimulated with IFNγ at 100 ng/ml for the indicated periods of time. Experimentally determined levels of phospho-STAT1, total STAT1 protein (immunoblot data received from total cellular lysates, the cytosolic cell fraction and the nuclei, respectively) and SOCS1 mRNA were normalized as described in the "Methods section". They are expressed in arbitrary units (a.u.) as averaged values of four to six independent experiments (± SEM). The immunoblot and PCR time series were scaled according to the requirements of the optimization methods. Confocal microscopy data were processed by calculating the ratio of nuclear versus cytoplasmic STAT1 concentration. The data are averaged values (± SEM) of 30 to 40 cells from three to four different images for each time point. Measured data are presented by blue symbols with error bars. Computational simulations: The simulated time courses resulting from the mathematical model with optimized parameters for STAT1, nuclear translocation of STAT1, STAT1P and SOCS1 mRNA are presented by solid red lines.