Effect of LY294002 on release of histamine and LTC4 and phosphorylation of MEK1 and ERKs after stimulation with anti-IgE Ab or FMLP.

(A) Effect of LY294002 on release of histamine and LTC4. Basophils were preincubated with DMSO (1:10 000 dilution) or LY294002 (10 μmol/L) for 10 minutes and were stimulated with or without FMLP (1 μmol/L) for 5 minutes or anti-IgE Ab (0.5 μg/mL) for 10 minutes. Reactions were stopped with the addition of ice-cold PAG, and the cells were microfuged. Supernatants were collected for histamine (closed column) and LTC4 (open column) measurements (n = 3). (B) Effect of LY294002 on phosphorylation of MEK1 and ERKs. Cell pellets were lysed and subjected to Western blot analysis as described in “Materials and methods.” The anti-MEK1 blot indicated essentially equal protein loading (data not shown). The Western blot shown is representative of 3 separate experiments.