Figure 3. IFNαR-induced MAPK requires a functional TCR, but, despite this, does not induce up-regulation of the same genes as TCR-induced MAPK signalling.

The Jurkat, JRT3-T3.5 (TCRβ^−/−) and PF2.4 (stably reconstituted with the TCRβ chain) cell lines were stimulated with (a) OKT3, which activates the TCR or (b) IFNα for the indicated time periods. Western blotting was then performed to determine the expression levels of phospho(Thr²⁰²/Tyr²⁰⁴)-ERK1/2 and ERK1/2. β-actin was used as a loading control. (c) Western blotting was used to determine the expression levels of phospho(Ser²¹⁷/Ser²²¹)-MEK1/2 and ERK1/2 in Jurkat, JRT3-T3.5 and PF2.4 cells that were stimulated with IFNα for the indicated time periods. β-Actin was used as a loading control. (d) Relative luciferase activity from an NFAT–luciferase reporter in Jurkat cells activated for the indicated times by immobilized anti-CD3 monoclonal antibody, either alone or in combination with IFNα. The results are expressed as RLUs (upper panel) or as relative luciferase activity in treated compared with untreated samples (fold activation; lower panel).