TABLE 3.

Okadaic acid blocks the activation of the ChAT promoter and of the RSV LTR by butyrate^a

Concn of okadaic acid (nM)	Luciferase activity with ChAT promoter (RLU/μg of protein, 103)		β-Galactosidase activity with RSV LTR (RLU/min/μg of protein, 103)
	− Butyrate	+ Butyrate	− Butyrate	+ Butyrate
0	4.02 ± 0.15	6.75 ± 0.10	1.07 ± 0.17	11.1 ± 1.6
200	5.03 ± 0.36	5.24 ± 0.17	0.48 ± 0.08	0.93 ± 0.38

^aCHP126 cells were cotransfected with construct F and RSV-lacZ (5 μg of each). Sixteen hours after transfection, sister cultures were treated with 200 nM okadaic acid or vehicle (0.25% DMSO). After a 30-min incubation, cultures were provided with 5 mM butyrate, as indicated, in the continued presence of okadaic acid. The cells were lysed 8 h later and tested for luciferase and β-galactosidase activities.