Fig (5) qHTS reproducibility of β-lactamase reporter gene assay. (A) LOPAC library was screened independently in CRE-bla CHO cells on three separate times. Linear correlations of EC_50s from 48 compounds with curve classes 1-3 in three independent screening yielded an average R² = 0.94 ± 0.02 ( 0.95, run 1 vs run 2; 0.94, run 1 vs run 3; and 0.92, run 2 vs run 3). 47 compounds were inactive in one or two runs and are colored gray in the figure. 1185 compounds were inactive in all three runs. (B) Examples of triplicate concentration-response curves for some of known PDE inhibitors, forskolin, rolipram and trequinsin hydrochloride, identified from the LOPAC library.