(A) Regulation of C/EBPε expression in HL60 cells by ATRA. Northern blot of total RNA (20 μg/lane) of HL60 cells exposed for various lengths of time to ATRA (5 × 10⁻⁷ mol/L). The top panel shows the hybridization with full-length C/EBPε cDNA probe, and the bottom panel displays the hybridization with β-actin cDNA probe as assessment of RNA quantities in each lane. (B) Regulation of C/EBPε expression in HL60 cells by DMSO. Northern blot of total RNA (20 μg/lane) of HL60 cells exposed for various lengths of time to DMSO (1.25%). The top panel shows the hybridization with full-length C/EBPε cDNA probe, and the bottom panel shows the hybridization with β-actin cDNA probe as assessment of RNA quantities in each lane.