Fig. 2. Temporal expression clusters during RA-induced differentiation of NT2/D1 cells. K-means clustering was performed on 953 transcripts where transcript vectors were normalized so that clustering was performed according to pattern rather than absolute level of expression. The profiles of the 20 expression patterns are shown, with the number of transcripts assigned to each cluster in parentheses. Each data point represents the weighted mean of the normalized transcript vectors within a cluster.