Figure 1. Kinase-dependent and -independent roles of Cdc28. (A) In late G1, Cdc28 phosphorylates the SBF-bound repressor Whi5. This triggers the release of Whi5 from the SBF, thus stimulating the transcription of the genes belonging to the G1 transcriptional program. (B) Cdc28/Cks1 and the 19S-regulatory particle of the proteasome are recruited to genes such as GAL1 for efficient transcriptional activation by promoting a decrease in nucleosomal density.