Fbxo7 gets proactive with cyclin D/cdk6.

Although all three D cyclins bind and activate cdks 2, 4 and 6, Fbxo7 has been characterised as a selective enhancer of cdk6 activity. It increases activation by directly facilitating cdk6 interaction with viral and cellular D cyclins. Fbxo7 overexpression has transforming activity in murine fibroblasts, and it is also highly expressed in human cancers, suggesting it is a potential oncogene. Fbxo7 has the ability to activate cell cycle regulators, and is part of an E3 ubiquitin ligase. We postulate Fbxo7 coordinates the ubiquitination of its substrates with cell cycle entry. It may therefore represent a means to integrate cell signals and control disparate biological processes during the early part of the cell cycle.