NFAT1-containing protein complexes bind a promoter region of A1 on activation in mast cells but not the macrophage cell line J774A.1. (A) ChIP reveals an increase of NFAT1-containing protein complexes bound to the A1 promoter in C57 cells stimulated with ionomycin for 3 hours compared with unstimulated cells. The binding is inhibited by pretreatment (10 minutes) of the cells with cyclosporin A before stimulation with ionomycin. Chromatin fragments were prepared and immunoprecipitated with antibodies against NFAT1, control IgG (negative control), and RNA polymerase II (positive control). The immunoprecipitated DNA and input DNA were analyzed by PCR using specific primer pairs for A1 resulting in PCR products covering the sequence shown in Figure 5A, and for the promoter of IL-13. Shown is a representative of 3 independent experiments. (B) Activation of the macrophage cell line J774A.1 by LPS for 3 hours increases complex formation of the NF-κB subunit RelA and chromatin of the A1 promoter region. On the contrary, the NFAT1-specific antibody does not pull down any chromatin bound protein complexes in J774A.1 but in ionomycin-activated C57 cells.