HDAC4 regulates apoptosis in Acan-Cre&lt;sup&gt;ERT2&lt;/sup&gt;;HDAC4&lt;sup&gt;d&lt;/sup&gt; &lt;sup&gt;/d&lt;/sup&gt; mice with osteoarthritis by downregulating ATF4. The gene discussed is HDAC4; the disease is osteoarthritis.