Induction of RARα2 by RA in RA-responsive, but not RA-resistant, leukemic cell lines.

(A) RT-PCR analysis of RARα1 and α2 expression in NB4 and HL60 cells that are sensitive (lanes 1-2 and 7-8) and resistant (lanes 3-6 and 9-10) to differentiation induction with RA. (B) Schematic diagram illustrating differential and lineage-specific effects of hematopoietic GFs on RARα expression. Given limiting RXR levels and the role of RXR as an obligatory heterodimerization partner for granulopoiesis- and erythropoisis-associated RAR and TR, respectively, the effects of hematopietic GFs on progenitor cell differentiation may, at least in part, be mediated by facilitating the formation of appropriate NR heterodimers.