Final answer:
HDAC inhibitors are being used to treat various forms of cancer by blocking the activity of histone deacetylases and altering gene expression.
Step-by-step explanation:
HDAC inhibitors are being used to treat various forms of cancer. These inhibitors work by blocking the activity of enzymes called histone deacetylases, which are involved in the regulation of gene expression. By inhibiting HDACs, these drugs can lead to changes in gene expression that can help kill tumor cells.