In addition to being expressed on the cell surface, PD-L1 is also released from tumor cells into the extracellular space to become free PD-L1, including exosome PD-L1 and soluble PD-L1 (sPD-L1; Frigola et al., 2011; Theodoraki et al., 2018). The gene discussed is CD274; the disease is neoplasm.