ENO2 and small cell lung carcinoma: SCLC arises from neuroendocrine cells of the APUD-system (amine precursor uptake and decarboxylation system) [67] and has two of the main biological features of these cells—production of L-DOPA-decarboxylase (L-3,4-dihydroxyphenylalanine- decarboxylase) and NSE (Figure 5a).