Table 3.

TrkA involvement in the axonal response to NGF-coated beads

Treatment	% Filopodial responses (n)
No treatment	71  (266)
25 μg/ml trkA antibody	20  (128)*
10 ng/ml NGF	29  (211)*
100 ng/ml NGF	32  (142)*
100 ng/ml BDNF	67  (267)**
70 μg/ml p75 antibody	68  (241)**
100 nmk252a	19  (127)*

Determination of axonal responses to NGF-coated bead contact was performed 3 hr after addition of beads to the culture. In the above experiments, cultures had been pretreated for a period of 1 hr before bead addition. Fisher’s exact test (one-tailed) was used to compare data from each experiment with the no treatment group, with the exception of the k252a experiment, which was compared with the DMSO-treated control (see Table 1). n refers to the number of bead–axon interactions scored.

*p < 0.0001; **p < 0.4.