FIGURE 3.

Activity of two FGF2 cis elements is increased by expression of Mll-Ell or overexpression of HoxA9 in myeloid leukemia cells. A, activity of the proximal and distal FGF2 cis elements is increased by Mll-Ell expression. U937 cells were co-transfected with minimal promoter/reporter constructs with multiple copies of the proximal or distal FGF2 cis elements (or control vector) and a vector to express Mll-Ell or empty control vector. Transfectants were analyzed for reporter activity with or without differentiation (with RA/DMF). Statistically significant differences are indicated by * or **. B, HoxA9 and HoxA10 activate two FGF2 cis elements in an additive manner. U937 cells were co-transfected with the minimal promoter/reporter constructs with multiple copies of the proximal or distal Hox binding FGF2 cis element (or control vector) and vectors to overexpress HoxA9, HoxA10, ½ HoxA9 + ½ HoxA10, HoxA9 with mutation of a conserved HD-Tyr residue (Ymut-HoxA9), HoxA10 with mutation of a conserved HD-Tyr residue (Ymut-HoxA10), or control vector. Plasmid vectors were adjusted so that the total amount of Hox expression vector was the same in Hox-overexpressing experiments. Transfectants were analyzed for reporter activity with or without differentiation. Statistically significant differences with versus without Hox-overexpression are indicated by * and **.