A systematic study [20] published in 2018 investigated T cell expression pattern in non-small cell lung cancer at the single-cell level, which confirmed that CD3D has differential expression levels not only in normal tissues and malignant tissues but also in the lung tissues and lymph nodes, implying that the gene is a potential biomarker distinguishing T cells from different tissues during the initiation and progression of non-small cell lung cancers. The gene discussed is CD3D; the disease is non-small cell lung carcinoma.