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. Author manuscript; available in PMC: 2014 Apr 17.
Published in final edited form as: Front Biosci (Schol Ed). 2012 Jan 1;4:831–839. doi: 10.2741/s303

Figure 1.

Figure 1

Figure 1

(A) Repression of p21 gene transcription by HDAC1/2. p21 inhibits the cyclin-cdk complex at the indicated phases (G1/S, S, and G2/M) to block cell cycle progression. HDAC1/2 binds to Sp1/Sp3 and is recruited to the promoter site of p21, leading to hypoacetylation of the promoter region and inhibition of p21 transcription. (B) Repression of p21 gene transcription by HDAC3/4. HDAC3/4 is recruited to the promoter site by binding to the Sp1/3 transcription factor as part of a larger repressor complex, NCo-R-SMRT, to inhibit p21 transcription.