The aim of the present study was to investigate whether protein kinase C (PKC) isoforms may be among the putative candidates implicated in the primary effects of the AT₂ receptor of Ang II. Western blot analyses revealed the presence of PKC,, and in NG108-15 cells. Following a 3-day treatment with 3 nM Gö6976, a specific inhibitor of classical PKC isoforms, cells were characterized by the presence of one elongated process similar to that observed following treatment with Ang II or with CGP42112, a selective AT₂ receptor agonist. Similar findings were observed in cells expressing a dominant negative mutant of PKC (K368A). Inhibition of PKC in NG108-15 cells also decreased cell number and proliferation. In conditions of acute stimulation, Ang II induced a time-dependent and transient inhibition of PKC activity, as well as a decrease in PKC levels associated with the membrane. Treatment of cells with Gö6976 was also found to inhibit p21^ras (between 1-10 min) but stimulated Rap1 activity (1-5 min) in a time-course similar to that of Ang II. Incubation of NG108-15 cells with Gö6976 (3 nM) inhibited basal p42/p44^mapk phosphorylation, but failed to interfere with its activation by the AT₂ receptor, indicating that inhibition of PKC is not directly involved in the Rap1-MEK-p42/p44^mapk cascade. Taken together, these results indicate that PKC is a primary target of the AT₂ receptor. Inhibition of PKC leads to a decrease in both p21^ras activity and cell proliferation, which may facilitate AT₂ receptor signaling through p42/p44^mapk thereby leading to neurite outgrowth.