SGK inhibits FKHRL1-dependent transcription. (A) CCL39 fibroblasts were transiently cotransfected with an empty vector (CTL) or a vector encoding WT FKHRL1 together with WT SGK, CA SGK (S422D) (SGK c.a.), or CA mutants of various protein kinases and the FHRE-Luc reporter construct. The day after transfection, cells were starved for 24 h and luciferase activity was assayed. Data are the means and variances for two independent experiments conducted in duplicate. (B) CCL39 fibroblasts were transiently cotransfected with an empty vector (CTL), a vector encoding CA SGK (S422D) (SGK c.a.), or a vector encoding CA Akt (Akt c.a.), together with vectors encoding WT FKHRL1 or the different FKHRL1 phosphorylation site mutants and the FHRE-Luc reporter construct. Luciferase assays were performed as described for panel A. Data are the means and variances for two independent experiments conducted in duplicate. (C) CCL39 fibroblasts were transiently cotransfected with an empty vector (CTL) or vectors encoding WT FKHRL1 or the different FKHRL1 phosphorylation site mutants and the FHRE-Luc reporter construct. The day after transfection, cells were incubated in the presence of IGF-I for 24 h and luciferase activity was assayed. Data are the means and variances of two independent experiments conducted in duplicate. Expression of the different mutants of FKHRL1 was monitored by immunoblotting with the anti-HA antibody. TM, triple mutant of FKHRL1 (T32A/S253A/S315A) .