Northern blot analysis of expression induction of the β-globin gene in PU.1-Δ E-sense clone 1 cells and PU.1-Δ A-sense clone 1 cells cultured under various conditions. Total RNA was extracted from the cells cultured for 72 hours in the ordinary medium or in the medium containing 1.5% DMSO alone or 1.5% DMSO and 100 μmol/L ZnCl₂ and was hybridized with ³²P-labeled probes.