A1 induction is abrogated by the calcineurin inhibitor cyclosporin A specifically in mast cells. BMMCs (A) and the mast cell line C57 (B) show increased expression of A1 mRNA when activated by IgER CL. The calcineurin inhibitor cyclosporin A abrogated the induction of A1. (C) The inhibitory effect of cyclosporin A on A1 induction was not observed in the macrophage cell line J774A.1 activated by LPS. Expression of mRNA was analyzed by RNase protection assays (RPA). Probing for L32 and Gapdh was used as a control. The data are from one (B) and 2 (A, C) independent experiments. Results have also been confirmed by RT-PCR analysis, which was repeated 3 times (data not shown).