Immunoblotting of K562 transfectants expressing full-length and domain-deleted Lu cDNA. Triton extracts prepared from K562 transfectants as described in Materials and Methods and solubilized red blood cell membranes were separated on 10% (wt/vol) polyacrylamide gels and probed with monoclonal antibodies BRIC 224 or BRIC 221 by Western blotting. r, red cell membranes; 1, Lu-del-2,3,4,5 transfectant; 2, Lu-del-3,4,5 transfectant; 3, Lu-del-4,5 transfectant; 4, Lu-del-5 transfectant; 5, Lu-full-length transfectant. M_r values for the stained bands were calculated from the migration of the indicated standard proteins.