HDAC9 and B-cell non-Hodgkin lymphoma: Valproic acid (class I HDAC inhibitor), romidepsin (HDAC1/2 inhibitor) or RGFP966 (HDAC3 inhibitor) upregulates MHC class I expression and costimulatory molecules, such as CD80 and CD86, in B-cell lymphomas (Deng et al., 2019).