FIG. 3.

p38 MAPK promotes NFATc activation but increases nuclear export of NFATc in T cells. (A) NFAT transcription activation mediated by NFATc was enhanced by MKK3b(E). EL4 T cells were transfected with NFAT-CAT in the presence of CMV-NFATc, calcineurin catalytic A subunit plus regulatory B subunit (CnA + CnB), and MKK3b(E) as indicated. CAT activities were determined 24 later. Data are reported as means and standard errors of the means. (B) EL4 T cells were similarly transfected with CMV-NFATc and/or MKK3b(E) or treated with A23187. Cytosolic and nuclear extracts were prepared 24 h after transfection, and the amounts of NFATc in the nucleus and cytoplasm were assessed by immunoblotting. α-Tubulin was used as a marker for the cytosol, and p300 was used as a marker for the nucleus. The quantity of NFATc was determined by densitometry and normalized by densitometric reading of the respective internal control (α-tubulin or p300). For ease of comparison, the quantity of cytoplasmic NFATc in untreated T cells was set at 1. N/Total, ratio of nuclear NFATc content to total (nucleus plus cytosol) NFATc content.