FIGURE 6.

Requirement of PKR activity for activation of MAPK pathways in primitive hematopoietic precursors. A, expanded human CFU-E cells were nucleofected with control siRNA or PKR siRNA, as described under “Materials and Methods.” Expression of PKR mRNA was assessed by real time RT-PCR and is shown as a percentage of the levels of control siRNA-treated cells. The data shown represent the means ± S.E. of two experiments. B, CFU-E cells were nucleofected with control siRNA or PKR siRNA. Equal amounts of protein were separated by SDS-PAGE and then immunoblotted with antibodies against PKR or GAPDH. C–F, CFU-E cells were nucleofected with either control siRNA or PKR siRNA for 24 h and were then treated with human TNFα (C and D) or IFNγ (E and F) for the indicated times. Equal amounts of protein were separated by SDS-PAGE and then immunoblotted with the indicated antibodies. CTRL, control.