Kmeans analysis of the normal immune response in studies of Maas et al. . Data are presented as the natural logarithm of the ratio of the experimental group to the control group indicated on the x-axis. Individual lines in the plot represent expression ratios of individual genes over the time course. Clustering patterns correspond to early upregulated genes (a), late upregulated genes (b) and genes that were downregulated throughout the followup period (c).