Of interest, all other protein markers tested (ROS1, PD-1, VEGFR3, VEGF, topoisomerase and tubulinβ-III) constituted an elevated expression signature with normal lung tissues having the lowest expression, NSCLC showing intermediate expression and the neuroendocrine subtype SCLC presenting the highest levels. The gene discussed is PDCD1; the disease is small cell lung carcinoma.