YAP associates with SRF and MRTF-A, and MRTF-A associates with TEAD and YAP, upon S1P stimulation. (A) Glioblastoma cells were serum starved for 24 h before being stimulated with S1P for 1 h. Cells were fractionated, and the nuclear lysate was immunoprecipitated with YAP or IgG control antibody. Immunoprecipitates were immunoblotted for YAP, TEAD, MRTF-A, and SRF. Whole nuclear fractions were analyzed for lamin A/C to demonstrate nuclear purity and for RhoGDI to demonstrate a lack of cytosolic contamination. (B) Glioblastoma cells were serum starved for 24 h before being stimulated with S1P for 1 h. Cells were fractionated, and the nuclear lysate was immunoprecipitated with MRTF-A or IgG control antibody. Immunoprecipitates were immunoblotted for MRTF-A, SRF, YAP, and TEAD. Whole nuclear fractions were analyzed for lamin A/C to demonstrate nuclear purity and for RhoGDI to demonstrate a lack of cytosolic contamination.