FIG. 3.

Induced expression of C/EBPα does not lead to apoptosis. IL-3-dependent BaF3 cells cultured in medium supplemented with IL-3 (B; negative control), or in conditions such that IL-3 was withdrawn for 24 h (A; positive control, showing apoptosis of nearly all cells as demonstrated by typical orange-yellow staining of the cell nuclei), as well as U937 cells stably transfected with the empty expression vector [U937(vect)#1] and cultured for 17 days in the presence of zinc (C), or transfected with the rat C/EBPα construct (U937α#2) and grown in the absence (D) or presence of zinc (E and F), were tested by TUNEL assay for apoptosis. Panels E and F show different fields from the same slide. The red arrow in panel F indicates an apoptotic cell.