(A) NGF-mediated protein tyrosine
phosphorylation. Cells were treated for 5 min with 100 ng/ml 2.5S
murine NGF or vehicle (PBS), lysed, resolved on a 10% polyacrylamide
gel, transferred to a nitrocellulose membrane, and probed with an
antiphosphotyrosine antibody (RC20). The NGF-induced P-Tyr containing
bands indicated by arrowheads correspond to erk1 (upper arrowhead) and
erk2 (lower arrowhead) based on relative molecular weights and
reprobing with erk1- and 2-specific antibodies (Lower).
(B) NGF-mediated NGFI-A gene induction. Cells were treated
with 100 ng/ml 2.5S murine NGF or vehicle (PBS) for 1 hr. The RNA was
harvested, resolved on a formaldehyde agarose gel, blotted to a
nitrocellulose membrane, and probed with a radiolabeled NGFI-A cDNA. An
apparent decrease in material going from left to right on the
autoradiogram is actually due to uneven transfer of the gel as can be
judged by a concomitant decrease in background signal. The efficiency
of transfer does not affect the conclusions drawn from the data.