Fig. 5. LB cells transfected with CD44v4-v10 cDNA mutated at the HA binding site lose their ability to bind HA and CS. (A) LB cells transfected with CD44v4-v10 cDNA (LB-TRv) (top panels) and LB cells transfected with CD44v4-v10 cDNA mutated at the HA binding site (LB-TRvM) (bottom panels) were indirectly analyzed by flow cytometry for expression of CD44 isoforms (pan CD44 and v6; left panels), as described in the legend to Fig. 2. In addition, the cells (right panels) were incubated with fluorescein-labeled HA (20 µg/ml) in the absence (FL-HA) or presence of unlabeled HA (1 mg/ml) (FI-HA+HA) or KM81 anti-CD44 mAb (100 µg/ml) (FI-HA+KM81) and analyzed by flow cytometry. Segregated histograms display HA binding; matched histograms indicate the inability to bind HA. (B) LB-TRv and LB-TRvM cell lines were subjected to flow cytometry to test their ability to bind FL-CS, as described in the legend to Fig. 3. LB-TRvM cells did not bind CS. AF, autofluorescence.