Fig. 7. The MAP kinase kinase inhibitor PD098059 (PD) increases the percentage of apoptotic cells among ISO-treated hemocytes, indicating that MAP kinase signaling is involved in mechanisms that protect hemocytes from apoptosis induced by ß-adrenergic signaling. PD098059 alone had no significant effect on the percentage of apoptotic hemocytes. Cells were maintained for 24h in the presence of 1 µM ISO or in the absence of drugs (Bas, basal level). Data are means and standard errors of three replicate experiments. Asterisks denote significant (P<0.01) differences from samples incubated in the presence of ISO alone.