Two MTD-induced cell cycle checkpoints.

This illustration shows the proposed relative location of the 2 known cell cycle arrest points in cells with MTD. SAC indicates spindle assembly checkpoint; G₁MTC, G₁ phase microtubule checkpoint. The centrosome cycle (1 or 2 MTOC indicates microtubule organizing centers) is shown to be coordinated with the DNA/chromosome cycle (2N or 4N DNA content). The arrests the cell cycle in G₁ phase between the shift from a low cdc2-expressing state to a high cdc2-expressing state. Some of the proteins implicated in each MT checkpoint are listed (see reference 15 for a recent review).