Within the COPD patients, the overall (across all the ROIs) PD-L1 protein expression was strongly directly correlated with the Forced Expiratory Volume in the 1 s (FEV1% predicted, which represents the proportion of a person's air that they can expire in the first second of forced expiration), indicating higher PD-L1 expression in the milder stages of the disease (Fig. 5A). The gene discussed is CD274; the disease is chronic obstructive pulmonary disease.