Characterization of antibodies by western blotting, absorption testing and blocking with epidermal growth factor. a. The neuropil fraction (see Materials and Methods) obtained from mouse hippocampus (lanes 1, 2), the L1-transfected cell lysate (lane 3), and the mock-transfected cell lysate (lane 4) were western blotted using the antiFLL1 (lane 1) and antiCTL1 (lanes 2–4) antibodies. AntiCTL1 antibody could detect the full-length (200-kDa) recombinant L1 in the lysate of transfected High5 insect cells (lane 3), whereas no positive band was detectable in the mock-transfected (control) High5 lysate (lane 4). b. Omission of primary antibody (-antiCTL1) resulted in no immunostaining (substantia nigra). c. Blocking of antiCTL1 antibody with epidermal growth factor (EGF) did not interfere with the immunostaining in the neighboring section of (b). d-f,d'-f'. Absorption of the antibody with L1 gene-transfected membrane (L1m) completely eliminated the immunostaining, whereas absorption of the antibody with mock-transfected membrane (Mock) had no effect (d'-f'). d,d': stria terminalis; e,e': substantia nigra; f,f': cerebellar cortex. b-e,d',e': Bar= 200 μm; f,f': Bar = 50 μm.