Fig. 5. Pathway preference in rblA-null cells. (A-C) rblA-null cells were stained with Cell Tracker CMFDA and mixed with excess wild-type cells (proportions 20:80) and allowed to develop. The stained cells predominate in the stalk (A) and the basal disk (B). In the spore head (C), they are found in the upper cup (top); a few form spores (bottom). (D) RblA-null cells transformed with actin6::-ß-galactosidase reporter were mixed with wild-type cells in the same proportion; at the slug stage, the marked cells predominantly occupy the prestalk zone (left) and the rearguard zone (right).