FIG. 6.

Inhibition of SCF-induced mitogenesis and c-kit transcript expression in FDCW2ER-pXG1 cells. (A) GATA-1-dependent inhibition of SCF-induced mitogenesis. The cytokine-induced mitogenesis of FDCW2ER-pXG1 (top) and control FDCW2ER (bottom) cell lines was assayed based on rates of Epo- and SCF-stimulated reduction of MTS. To account for any minor differences in plating, values were normalized based on maximal responsiveness to IL-3. (B) GATA-1-mediated inhibition of c-kit transcript expression in FDCW2ER-pXG1 cells. c-kit transcript levels in FDCW2ER-pXG1 cells versus control FDCW2 and FDCW2ER cells were assayed by Northern blotting of polyadenylated RNA. Also analyzed were FDCW2ER-pXG1 cells transfected stably with pCINeo vectors encoding either GATA-1 to reinforce its expression (FDCW2ER-pXG1 c.12pCG1 cells) or EKLF as a control (FDCW2ER-pXG1 c.12pCEKLF cells).