(A) Luciferase activity of stably transfected −916 bp and −916(d)S LF promoter plasmids in uninduced and Epo-induced (48 h) 32Dwt18 cells. The fold increase in reporter gene activity following Epo induction (fold induction) was calculated as luciferase activity + Epo per 1 × 10⁶ viable cells/luciferase activity − Epo per 1 × 10⁶ viable cells. Three independent experiments were performed; standard deviations are indicated by error bars. (B) Northern blot analysis of 32Dwt18 cells induced to undergo neutrophil maturation following Epo induction. Ten micrograms of total RNA from uninduced or 2-day Epo- and 4-day Epo-induced 32Dwt18 cells was electrophoresed on a 1% formaldehyde/agarose gel and blotted onto a nitrocellulose filter. The filter was first probed with [α-³²P]dCTP–labeled LF cDNA (top) and later stripped and reprobed with an [α-³²P]dCTP–labeled β-actin probe to ensure equal loading of RNA in each lane (bottom).