Type I interferons (IFNs) are potent regulators of normal hematopoiesis in vitro and in vivo,
but the mechanisms by which they suppress hematopoietic progenitor cell growth and
differentiation are not known. In the present study we provide evidence that IFNα and IFNβ
induce phosphorylation of the p38 mitogen-activated protein (Map) kinase in CD34+-derived
primitive human hematopoietic progenitors. Such type I IFN-inducible phosphorylation of
p38 results in activation of the catalytic domain of the kinase and sequential activation of the …