The mechanism of action of NGF has continued to provide a challenging and formidable
problem in signal transduction. NGF can bind independently to two different receptors, the
trkA tyrosine kinase receptor and the p75 neurotrophin receptor, which are involved in many
different signaling events. In addition to promoting cell differentiation survival, NGF can
paradoxically be an inducer of cell death. Several receptor mediated mechanisms are
proposed to explain how NGF might act as a trophic factor and as a cell killer. The survival …