Fig. 6. Inhibition of NGF induced gp140^TrkA internalization with anti-p75^NTR antibodies.

A, PC12 cells were incubated prior to (30 min) and during NGF treatment with 8 μg/ml of the antibody MC192 directed against the p75^NTR extracellular domain. NGF treatment was carried out for 30 min with concentrations ([NGF]) ranging from 0 to 50 ng/ml. At the end of the incubation time, the TrkA cell surface level was evaluated by flow cytometric analysis (see “Materials and Methods” for details). Values are means ± S.E. of four independent experiments. B, PC12 cells were incubated prior to (30 min) and during NGF treatment with a 1:100 dilution of REX serum directed against the extracellular domain of p75^NTR. NGF treatment was carried out for 30 min with concentrations ([NGF]) ranging from 0 to 50 ng/ml. At the end of the incubation time, cell surface level of TrkA was evaluated by cell surface biotinylation. Values are means ± S.E. of three independent experiments.