Importantly, we also found that l-fuc does not alter cell surface levels of programmed cell death ligand 1 (PD-L1) in mouse or human melanoma cells (Extended Data Fig. 6a), suggesting that the l-fuc-associated tumor suppression in these models is attributed to determinants beyond the PD1–PD-L1 axis. The gene discussed is PDCD1; the disease is neoplasm.