Fig. 4.

The binding of anti-β-endorphin antibody to β-endorphin-expressing SK-N-MC cells is partially inhibited by soluble Met-enkephalin as assessed by cytofluorometry. The human neuroblastoma cell line SK-N-MC expressing both enkephalin and β-endorphin was intracellularly stained with control rabbit non-immune serum IgG (a) or rabbit anti-β-endorphin polyclonal IgG antibodies in the absence (b) or in the presence of an excess of soluble β-endorphin (c) or Met-enkephalin (d). The figure shows one representative experiment out of three performed. Schematic interpretation of the experiments is shown on the right of each histogram