Myt-1 mediated phosphorylation of Cyclin B:Cdc2 complexes Wee1-mediated phosphorylation of Cyclin B1:phospho-Cdc2 complexes PathwayStep4478 PathwayStep4481 G2/M DNA replication checkpoint Reactome Database ID Release 4369478 Reactome, http://www.reactome.org ReactomeREACT_1846 The G2/M DNA replication checkpoint ensures that mitosis is not initiated until DNA replication is complete. If replication is blocked, the DNA replication checkpoint signals to maintain Cyclin B - Cdc2 complexes in their T14Y15 phosphorylated and inactive state. This prevents the phosphorylation of proteins involved in G2/M transition, and prevents mitotic entry.<p>Failure of these checkpoints results in changes of ploidy: in the case of mitosis without completion of DNA replication, aneuploidy of <2C will result, and the opposite is true if DNA replication is completed more than once in a single cell cycle with an overall increase in ploidy. The mechanism by which unreplicated DNA is first detected by the cell is unknown.