The upregulation of PD-L1 on the surface of MM cells upon treatment with panobinostat and IFN-γ in combination remained at day 2 (Supplementary Figure 1E), when IRF1 protein levels decreased in MM cells (Figure 3D), suggesting limited contribution of IRF1 to the sustained PD-L1 upregulation by HDAC inhibition in the presence of IFN-γ. This evidence concerns the gene HDAC9 and Miyoshi myopathy.