Substantial evidence suggests that the transient production of H 2 O 2 is an important
signaling event triggered by the activation of various cell surface receptors. Understanding
the intracellular messenger function of H 2 O 2 calls for studies of how receptor occupation
elicits the production of H 2 O 2, what kinds of molecules are targeted by the produced H 2 O
2, and how H 2 O 2 is eliminated after the completion of its mission. Recent studies suggest
that growth factor–induced H 2 O 2 production requires the activation of PtdIns 3-kinase. The …