Dominant expression trends in VL muscles , brain cortex and kidney cortex. Plots show the major trends identified from the significant age-regulated probes using k- means with Euclidean distance as metric (A) or absolute correlation as metric (B). The X-axis represents the age in years and the Y-axis the fold change (log2) after normalization to the average. Shown are the major age-regulated trends, where red circles interconnected by red lines represent the cluster centroids, blue and black lines are the 95th or 99th percentiles, respectively. The number of probes in each cluster is indicated between brackets. Arrowheads indicate the age-positions.