Concordant to the role of AIP4 on PD-L1 monoubiquitination, clomipramine treatment of lung epithelial and cancer cells effectively inhibited PD-L1 monoubiquitination and enhanced PD-L1 protein abundance in the cells and on the cell surface (Fig. 6a, b and Supplementary Fig. S8c, d). This evidence concerns the gene CD274 and cancer.