Induction of MPO RNA by C/EBP requires new protein and RNA synthesis. 32D-WT-ER-1 cells in IL-3 were exposed to estradiol for 0 or 8 hours. A third culture was exposed to cycloheximide (CHX) for 8 hours. A fourth culture was exposed to CHX for 30 minutes and then to CHX with estradiol for 8 hours. A fifth culture was exposed to Actinomycin D (Act) for 8 hours. A sixth culture was exposed to Act for 30 minutes and then to Act with estradiol for 8 hours. Total cellular RNAs prepared from each culture were then subjected to Northern blotting for MPO and 18S RNAs.