FIG 2.

MRTF-A is activated by S1P through RhoA and ROCK signaling. (A) Twenty-four-hour serum-starved glioblastoma cells were pretreated with 1 μg/ml C3 exoenzyme (24 h) or 10 μM Y-27632 (1 h). Cells were then stimulated for 1 h with 0.3 μM S1P. MRTF-A subcellular localization was determined by immunofluorescence staining for endogenous MRTF-A (green) along with DAPI staining to show nuclei (blue). (B) Cells were transfected with a TCF-independent, SRF promoter-driven firefly luciferase reporter construct (SRE.L-Luc) for 24 h. Cells were serum starved for 24 h prior to being pretreated with 1 μg/ml C3 exoenzyme (24 h) or 10 μM Y-27632 (1 h), stimulated with 0.3 μM S1P for 8 h, and assayed for luciferase expression. Data shown are normalized to Renilla luciferase activity and expressed as fold changes over the control level. **, P < 0.01 versus control (n = 6).