AbstractWe have identified a new subline of PC12 pheochromocytoma cells (PC12D cells) in which neurites are extended within 24 hr in response to cAMP‐enhancing reagents as well as in response to nerve growth factor (NGF), but not in response to epidermal growth factor or phorbol diester. Anti‐NGF antiserum did not affect forskolin (FRK)‐induced neuritic recruitment. FRK‐induced neurites exhibited growth cones and contained secretion granules and many parallel arrays of microtubules as was the case with NGF‐induced neurites. FRK, but not NGF, increased the levels of intracellular cAMP and activated adenylate cyclase in the membrane fraction. Both NGF and FRK enhanced the activities of tyrosine hydroxylase (TH), acetylcholinesterase (AchE), and ornithine decarboxylase (ODC), but not the levels of neuron‐specific enolase. Enhanced levels of intracellular cAMP mimicked the effects of NGF on neuritic growth, TH, AchE, and ODC activities inPC12D cells, even though NGF does not act through elevation of lev