CD274 and cancer: The inhibitory effects of kifunensine on PD-L1 activities in the cancer cells suggest that the activity of α-mannosidase I, which is the main enzyme inhibited by kifunensine [29,30], is pivotal for PD-L1-induced effects in breast tumor cells; our data also imply, via the use of swainsonine, that N-linked glycosylation by α-mannosidase II [29,30] plays a role in this process.