Angiotensin II (Ang II) stimulates growth and mitogenesis in bovine adrenal glomerulosa cells, but little is known about the signaling pathways that mediate these responses. An analysis of the growth-promoting pathways in cultured bovine adrenal glomerulosa cells revealed that Ang II, acting via the AT1 receptor, caused rapid but transient activation of mitogen-activated protein kinase (MAPK), with an ED50 of 10-50 pM. Although neither Ca2+ influx nor Ca2+ release from intracellular stores was sufficient to activate MAPK, Ca2+ appeared to play a permissive role in this response. A major component of Ang II-induced MAPK activation was insensitive to pertussis toxin (PTX), although a minor PTX-sensitive component could not be excluded. Ang II also induced the rapid activation of ras and raf-1 kinase with time-courses that correlated with that of MAPK. Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate was sufficient to activate both MAPK and raf-1 kinase. However, whereas PKC depletion had no effect on Ang II-induced raf-1 kinase activation, it attenuated Ang II-induced MAPK activation. Ang II also stimulated a mobility shift of raf-1, reflecting hyperphosphorylation of the kinase. However, unlike its activation, raf-1 hyperphosphorylation was dependent on PKC and its time-course correlated not with activation, but rather with deactivation of the kinase. Taken together, these findings indicate that Ang II stimulates multiple pathways to MAPK activation via PKC and ras/raf-1 kinase in bovine adrenal glomerulosa cells.