(A) Quiescent NIH 3T3, E25-48, and B35-41 cells were incubated with DMEM containing 5 μg/ml insulin (open bars), 20% calf serum (hatched bars), or 30 ng/ml NGF plus 5 μg/ml insulin (filled bars). Results are expressed as the mean of three independent experiments assayed in duplicate (+SEM).
(B) E25-43 cells were stimulated by the indicated amounts of NGF either in the absence (open circles) or presence (filled circles) of a 10-fold molar excess of anti-NGF monoclonal antibody clone 27/21 (Boehringer Mannheim).