The HDAC inhibitors are already being incorporated into cancer treatment in humans (Moufarrij et al., 2020) and several studies show that the modulation of the expression of these enzymes favors the immune system and the transcription of tumor suppressor genes (Lansigan and Foss, 2010; Fang et al., 2015; Lu et al., 2020). Here, HDAC9 is linked to cancer.