(A) Recombinant CerADPr was incubated with 5 mM NAD+ for 24, 36, or 48 hr. An aliquot of each reaction was analyzed by PEI-cellulose thin layer chromatography. (B) CerADPr, CerADPr(E431D), or ExoS was incubated with 5 mM NAD+ for 24 hr. An aliquot of each reaction was then subjected to PEI-cellulose TLC. Plates were imaged and the amount of ADP-ribose produced was quantified by densitometry and normalized to an ADP-ribose standard. Quantification is from 3 independent experiments, error bars display SEM. An unpaired t-test was performed on selected columns *p<0.05 **p<0.01