Fig. 4. Induced expression of AKP- but not KP-Jafrac2 causes induction of apoptosis in S2 cells. Similarly, AVA- and AKP-Rpr but not VA- and KP-Rpr promote cell death. The indicated Ub fusion constructs were co-transfected with a lacZ reporter plasmid, and 24 h post-transfection cells from each well were divided into two dishes to avoid variations in transfection efficiencies. Expression of the indicated constructs was induced by copper sulfate and cells were examined for β-galactosidase (β-gal) activity. (A–D) and (I–L), untreated cells; (E–H) and (M–O), cells treated with copper sulfate (induced state).