SYP and neoplasm: To define the signatures of NSCLC tumours with neuroendocrine features, we first determined the protein levels of neuroendocrine markers, including CgA, CD56, and Syp, in NSCLC cells, and we found that these markers were undetected in A549, HCC827 and PC9 human lung adenocarcinoma cells, except for CgA (Fig. 1a).