Fig. 1.

Anti-GHR_ext-mAb specifically inhibits GH-induced proliferation. 32D-GHR cells (25,000 per well) were seeded in triplicate in 96-well plates and then serum starved. Cells were treated ± GH (100 ng/ml) for 48 h ± anti-GHR_ext-mAb (6 or 12 μg/ml) or anti-GHR_cyt-mAb (12 μg/ml), as indicated. Viable cell number was then estimated by MTT assay, as in Materials and Methods. Data (mean ± sem of triplicate determinations) for this experiment are indicated as the GH-induced fold increase in OD₄₉₀ relative to the value determined when no GH was added. Note that GH-induced proliferation is specifically inhibited by anti-GHR_ext-mAb and not by anti-GHR_cyt-mAb. The experiment shown is representative of three such experiments.