The importance of endogenous antagonists in intracellular signal transduction pathways is becoming increasingly recognized. There is evidence in cultured mammalian cells that Pyst1/MKP3, a dual specificity protein phosphatase, specifically binds to and inactivates ERK1/2 mitogen-activated protein kinases (MAPKs). High-level Pyst1/Mkp3 expression has recently been found at many sites of known FGF signaling in mouse embryos, but the significance of this association and its function are not known.
Eblaghie, M. C., Lunn, J. S., Dickinson, R. J., Münsterberg, A. E., Sanz-Ezquerro, J. J., Farrell, E. R., Mathers, J., Keyse, S. M., Storey, K., & Tickle, C. (2003). Negative feedback regulation of FGF signaling levels by Pyst1/MKP3 in chick embryos. Current Biology, 13(12), 1009-18. https://doi.org/10.1016/S0960-9822(03)00381-6