Inhibition of all-trans retinoic acid-induced granulocytic differentiation of WEHI-3B D+ cells by forced expression of SCL (TAL1) and GATA-1

All-trans retinoic acid (ATRA) induces granulocytic maturation of WEHI-3B D+ leukemia cells and LiCl enhances this maturation, while WEHI-3B D− cells are non-responsive to ATRA. Transfection of SCL, expressed in D− but absent in D+ cells, into D+ cells, caused resistance to ATRA, while transfection of GATA-1 into D+ cells produced resistance to the combination of ATRA and LiCl. SCL expression in D+ cells did not induce the expression of c-Kit, a putative target gene for SCL. LiCl, known to inhibit some kinases by displacing Mg2+, did not affect tyrosine kinase activity of the cytoplasmic domain of c-Kit.