Cell Division

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Open Access Review

Restriction beyond the restriction point: mitogen requirement for G2 passage

Floris Foijer and Hein te Riele*

Author Affiliations

Division of Molecular Biology, the Netherlands Cancer Institute, Plesmanlaan 121, 1066CX, Amsterdam, The Netherlands

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Cell Division 2006, 1:8 doi:10.1186/1747-1028-1-8

Published: 18 May 2006

Abstract

Cell proliferation is dependent on mitogenic signalling. When absent, normal cells cannot pass the G1 restriction point, resulting in cell cycle arrest. Passage through the G1 restriction point involves inactivation of the retinoblastoma protein family. Consequently, loss of the retinoblastoma protein family leads to loss of the G1 restriction point. Recent work in our lab has revealed that cells possess yet another mechanism that restricts proliferation in the absence of mitogens: arrest in the G2 phase of the cell cycle. Here, we discuss the similarities and differences between these restriction points and the roles of cyclin-dependent kinase inhibitors (CKIs) herein.