Effect of macrophage-like differentiation of HL-60 cells on their expression of C/EBPε mRNA. HL-60 cells were cultured with TPA (2 × 10⁻⁸ mol/L) and cells were harvested for RNA extraction after 0.5, 2, 6, 24, and 48 hours. Northern blot analysis was performed using a ³²P-labeled cDNA probe for C/EBPε.