Effects of combined administration of MAPK inhibitorsin vitro. Human CD4+ T cells were preincubated either with increasing doses of U0126 alone (solid line) or in combination with SP 600125 (dashed line) of with SB 203580 (dotted line). Doses of the MAPK inhibitors are specitied in the text. After that, cells were stimulated with α-CD3/B7-2 Fc (A, B) or α-CD3/B7-H2 Fc (C, D) for 8 hours. IFNγ (A, C) and IL-13 (B, D) cytokine mRNA was measured by real-time RT-PCR. Dose-response curves were determined and IC50 values were calculated. Data are representative of three different donors.