Competitive Western blot analysis with epitopic peptides of L514S and L552S. Patient pleural effusions (300-fold dilution; 659-23, G244, and 298-19) were incubated 30 min in the absence (left) or presence (right) of L514S peptide #18 or L552S peptide #29 at a concentration of 10 µg/ml. They were then assessed by Western blot analysis.