CDKN1A and acute myeloid leukemia: Furthermore, reduced p21 expression could be dramatically restored by HDAC inhibition using Trichostatin A. Reanalysis of ChIP‐seq data in Kasumi‐1 AML cells showed that knockdown of the RUNX1T1 fusion protein was associated with increased global acetylation, including the CDKN1A (p21) promoter.