Hippo pathway key to ploidy checkpoint.

Tetraploid cells generated by abnormal cell division are often arrested during the cell cycle or cleared by apoptosis. Evasion of these defense mechanisms leads to genomic instability and tumorigenesis. In this issue, Ganem et al. report that extra centrosome-induced activation of the Hippo pathway kinase LATS2 is a key mechanism of tetraploidy-induced cell-cycle arrest.