Angiotensin-(1-7) [Ang-(1-7)] is generated in part via ACE2-dependent degradation of angiotensin II (Ang II). In proximal tubular cells, Ang-(1-7) inhibits Ang II-stimulated phosphorylation of the mitogen-activated protein kinases (MAPKs) p38, extracellular signal-related kinase (ERK1/ERK2), and c-jun N-terminal kinase (JNK), suggesting that Ang-(1-7) protects against Ang II-mediated tubulointerstitial injury. We determined the effect of Ang-(1-7) on signaling and growth responses in cultured human mesangial cells. Ang-(1-7) increased phosphorylation of p38, ERK1/ERK2 and JNK MAPKs, which was blocked by the Ang-(1-7) antagonist A-779. Neither the AT₁ receptor antagonist losartan, nor the AT₂ antagonist PD123319 affected specific binding of [¹²⁵I]-Ang-(1-7) or Ang-(1-7)-stimulated p38 phosphorylation. Ang-(1-7) increased cell arachidonic acid release, an effect blocked by A-779. The p38 MAPK antagonist SB202190 completely prevented Ang-(1-7)-stimulated release of arachidonic acid, whereas inhibitors of ERK or JNK had no effect. Ang-(1-7) significantly enhanced DNA synthesis, and increased production of transforming growth factor-1 (TGF-1), fibronectin, and collagen IV. Both A-779 and SB202190 blocked the Ang-(1-7)-stimulated increases in TGF-1, fibronectin and collagen IV. These data indicate that Ang-(1-7) activates MAPK phosphorylation via binding to a specific receptor in human mesangial cells. Stimulation of p38 MAPK phosphorylation by Ang-(1-7) leads to release of arachidonic acid and production of TGF-1 and extracellular matrix proteins. We conclude that Ang-(1-7) exerts growth-stimulatory effects in human mesangial cells.