Figure 1. (A) Relationship between genes induced by genotoxins. Venn diagrams showing the overlap between genes activated in response to MMS, HU and CPT (top diagram) and between the checkpoint-dependent genes induced by HU, MMS and Nrm1-regulated genes (bottom diagram). (B) Regulation of G₁/S transcription by the checkpoint. Rad53 phosphorylates Nrm1, blocking its binding to MBF and, thus, allowing the MBF-regulated transcription to remain active during S phase.