Immunofluorescence labeling evidence for expression of neuroendocrine markers 5HT (A, F, K, P), chromogranin A (B, G, L, Q), N–CAM (C, H, M, R) and CFTR, demonstrated by two anti–CFTR antibodies, M24–1 (D, I, N, S) and TAM18 (E, J, O, T) monoclonal antibodies in SCLC cell lines H146 (K–O) and H345 (P–T) and carcinoid cell line H727 (F–J). The control tumor cell line T84 (A–E) shows no expression of neuroendocrine markers but expresses CFTR as expected. NHLF (negative control) do not stain with anti-CFTR antibodies (U, V). For more information see article by Pan and coworkers on page 553.