Figure 5
Transcriptional activity of CREB and CREB mutants in the presence of a nuclear targeted mutant of the catalytic subunit of cAMP-dependent protein kinase. One of the reporter plasmids pG6PCRE1/CRE2luc, pG6PCRE1mut/CRE2luc pG6PCRE1/CRE2mutluc (A), pG6PCRE1luc, pG6PCRE2luc (B), or pTNFα(CRE/AP1)2luc (C) (1 μg/plate) was transfected into HepG2 cells together with the pRSVβ internal standard plasmid (2 μg/plate) and the "empty" expression vector pCMV5 or an expression vector encoding either CREB, CREBS133A, or K-CREB (20 ng plasmid/plate). In addition, an expression vector encoding NLSCα (100 ng/plate) was transfected. Forty-eight hours post-transfection cell extracts were prepared and the β-galactosidase and luciferase activities of these extracts were determined. The data are presented as the ratio of luciferase activity (light units) to β-galactosidase units (OD units) measured in the cell extracts. The mean +/- SD is depicted.