Detection of iNOS protein in B-CLL cell extracts by Western blotting. Homogenates of five different B-CLL cell samples (lanes 1 through 5) were electrophoresed on acrylamide, blotted onto membranes, and probed with a monoclonal anti-iNOS MoAb (clone 54) and revealed by ECL. Right lane, crude extract from IFN-γ–stimulated murine RAW 264.7 macrophage cell line (positive control of iNOS expression).