Fig (4) Screening test of β-lactamase reporter gene assay in CREbla CHO cells in 1536-well format. Column-1 is a concentration response curve of IBMX, the known potentiator in duplicate, in the presence of 30 nM NKH 477. Column-2 is a concentration response curve of IBMX in the absence of NKH 477. Column-3 was the negative control with assay buffer only. Column-4 to 48 was DMSO with 30 nM NKH 477.