Mouse erythroleukemia (MEL) cells transformed by Friend virus and induced to undergo erythroid differentiation by treatment with hexamethylenebisacetamide (HMBA) increase erythroid specific 5-aminolevulinate synthase (ALAS-E) mRNA levels by 4-15-fold and decrease "housekeeping" 5-aminolevulinate synthase (ALAS-N) mRNA levels by 1.2-1.4-fold.