Several studies have previously shown that histone deacetylase 4 (HDAC4) can regulate endoplasmic reticulum stress-induced apoptosis through the activating transcription factor 4 (ATF4)/CAAT/enhancer binding protein homologous (CHOP) signaling pathway, thereby affecting the progression of osteoarthritis (OA). This evidence concerns the gene ATF4 and osteoarthritis.