5-HT induction of c-fos gene expression requires reactive oxygen species and Rac1 and Ras GTPases.

Serotonin (5-HT) stimulates superoxide release, phosphorylation of p42/p44 mitogen-activated protein kinase (MAPK), and DNA synthesis in bovine pulmonary artery smooth muscle cells. Both p42/p44 MAPK and reactive oxygen species (ROS) generation are required for 5-HT-induced growth in SMC. Agents that block the production of ROS, or ROS scavengers, block MAPK activation by 5-HT.