Model of Gata1 function in DCs. Gata1 and PU.1 are coexpressed during DC development. We propose that Gata1 counteracts apoptotic signals at 2 critical developmental stages affecting survival of DC precursors and of TLR-stimulated DCs. Upon TLR4 stimulation, Gata1 levels increase and PU.1 is down-regulated, resulting in an antiapoptotic response as measured by Bcl2 and BclX up-regulation versus Casp3 down-regulation. In addition, this triggers the expression of responsive cytokines such as IFN-γ, thus ensuring optimal activation of the adaptive immune response.