The irreversibility of cell-cycle transitions is commonly thought ... the CKI is rapidly phosphorylated and consequently ubiquitinated by an SCF complex and degraded by the proteasome (Fig.

Surprisingly, new work indicates that this function of Cks1 is independent of CDKs and links Cks1 with the Skp2 subunit of the SCF ubiquitin ... workings of the cell division cycle machinery ...