Effect of actinomycin D on the expression of transcripts 50 and 134.

TF-1 cells were starved for 4 hours (lane 1) and exposed for 4 hours (transcript 134) or 8 hours (transcript 50) to either GM-CSF alone (lane 2), or actinomycin D alone (lane 3) or actinomycin D and GM-CSF. Total RNA was submitted to Northern blot analysis using specific probes for detection of transcripts 50, 134, or 28S as described in Figure5.