Effect of actinomycin D on expression of OSM transcripts induced by LPS plus GM-CSF. PMN (5 × 10⁷) were incubated for 15 minutes in the presence or absence of 5 μg/mL actinomycin D (ACT D) and then stimulated for 1 hour with LPS (100 ng/mL) plus GM-CSF (100 U/mL). Controls cells (CTRL) were incubated in the medium alone. Total RNA was extracted and processed for Northern blot analysis of OSM and actin mRNAs as described in Materials and Methods. Results are from one experiment representative of two.