Fig. 8.

Ras oncogene impairs cAMP signaling by acting downstream of cAMP production. A, Transient transfection assay of NUE reporter activity in Cl11 cells treated or not with 4OHT either in the absence or in the presence of FSK and IBX or a combination of them for 48 h as reported in the figure. NUE activity is expressed as percentage of the activity obtained in untreated cells. B–D, Western blot analysis of CREB phosphorylation at Ser133 (pCREB). Total CREB (CREB) was used to normalize. B, Cl11 and SPRT-TSHr-expressing clones (T4 and T17) treated 24 h with or without 4OHT. C, Cl11 cells treated 24 h with or without 4OHT either in the presence or absence of FSK/IBX. D, QWB analysis of three wild-type FRTL-5 stable clones expressing only the resistance gene (wt clones) and three FRTL-5 stable clones expressing RasV12 (RasV12 clones). pCREB signal quantitation for three independent experiments is reported on the right side. *, P ≅ 0.03. wt, Wild type.