Figure 7.

Schematic diagram of the interaction of p38 and ERK MAP kinases, MKP-3, and TNF-α gene expression in monocytes exposed to crocidolite asbestos. The p38 MAP kinase is a positive regulator, and the ERK MAP kinase is a negative regulator of TNF-α gene expression. The differential activation of the p38 and ERK MAP kinases is due, in part, to asbestos-induced MKP-3 expression. The dynamic balance of MAP kinase signaling in cells overexpressing MKP-3 suggests that an environment favoring p38 MAP kinase activation is necessary for TNF-α production in monocytes exposed to asbestos.