Minimal gene clusters continue cycling under MD exposure but not under HP exposure. Shown are average expression time courses for small clusters of genes presenting a close-to-normal expression patterns under MD treatment, but not HP. Black lines represent normal cell cycle expression (Spellman et al., 1998); red and magenta lines, HP1 and HP2 time courses, respectively; blue and light blue lines, MD1 and MD2 time courses, respectively. (A) G2/M cluster, comprised of SUR7, BUD3, YOR315W, ALK1, HST3, SWI5, CLB1, CLB2, YNL058C, YNL057W, IQG1, CHS2, SRC1, and HEK2. (B) M/G1 cluster, SIC1, YNL046W, CYK3, YLR194C, ASH1, AMN1, NIS1, TEC1, DSE4, YPL158C, PCL9, DSE3, EGT2, PST1, PIR3, PIR1, HSP150, and GPA1. (C) G1 cluster, YJL217W, GIC2, SHQ1, DSE2, DSE1, SCW11, CTS1, and RME1.