Epitope analysis of L514S- and L552S-specific Abs in NSCLC patients. For the competitive ELISA (left panels), plates were coated with L514S (upper left panel) or L552S (middle and lower left panels) protein and blocked with 10% NFDM/PBS. Diluted (300x) pleural effusion, with or without pooled or individual peptides of L514S or L552S, was then added to the plates. For the peptide-based ELISA (right panels), pooled and individual peptides of L514S (upper right panel) or L552S (middle and lower right panels) were coated on 96-well plates. After the plates were blocked with 10% NFDM/PBS, diluted (300x) patients’ LPEs were added. After washing, both plates were developed with HRP-conjugated antihuman IgG and substrate.