1. Cell-Cycle Checkpoints: Keeping mitosis in check
Tim Humphrey, Tamar Enoch 
Current Biology 
Volume 5, Issue 4, Pages (April 1995)
DOI: /S (95)

2. Figure 1
Model for the molecular basis of the phenotypes of different classes of checkpoint mutant. In wild-type cells, the presence of a replication complex activates a checkpoint that inhibits mitosis. Class 1 mutants have defects in this checkpoint pathway. Class 2 mutants fail to assemble a replication complex, so the checkpoint is not activated. Polymerase ∈ mutants, which are viable but checkpoint-defective, have lost the ability of the replication complex to activate the checkpoint.
Current Biology 1995 5, DOI: ( /S (95) )