The M/G1 clusters. The transcription profiles are displayed as described in the legend to Figure ​Figure1.1. (A) MCM cluster. The MCM genes are involved in initiation of DNA replication and are coregulated during the M/G1 transition of the cell cycle. (B) SIC1 cluster. Twenty-seven genes that peak at the M/G1 boundary form a subcluster. (C) MAT cluster. This is a cluster of 13 coregulated genes expressed at the M/G1 boundary, many of which are involved in mating.