S. cerevisiae cell cycle regulation. (a) The histogram of mean absolute errors (MAE) shows that the majority of the genes were fitted reasonably well. MAE is defined as . (b) The dynamics of the TFAs for 11 transcription factors involved in cell cycle regulation. Different stages in the cell cycle are indicated by the color code. Rows I, II, and III represent experiments using different synchronization methods: elutriation, α factor arrest, and arrest of a cdc15 temperature-sensitive mutant, respectively. Shaded areas span four standard deviations (estimated by using a bootstrap technique as explained in Appendix 3). (c) The comparison between expression levels and activities of selected transcription factors shows that the expression levels do not exhibit an oscillatory behavior, whereas TFAs do.