(A) CAT activity in K562 cells transiently transfected with a pCAT positive control vector, pCAT B negative control vector, and pCAT B containing RsaI-BamHI,XhoI-BamHI, SmaI-BamHI, NaeI-BamHI, and NaeI-BamHI (del) inserts. (B) CAT activity in CHO cells transiently transfected with a pCAT positive control vector, pCAT B-negative control vector, and pCAT B containingRsaI-BamHI, XhoI-BamHI, SmaI-BamHI, NaeI-BamHI, andNaeI-BamHI (del) inserts. Transfection reactions were normalized by use of PAP assays, as detailed in Materials and Methods. Mean ±SD of six different experiments, each performed in duplicate, are shown. CAT activity was normalized to the CAT control transfected cells, which were arbitrarily set at 100%.