FIG 1.

CCN1 expression is highly and rapidly increased by S1P in a Rho-dependent manner. (A) Twenty-four-hour serum-starved glioblastoma cells were treated with 500 μM carbachol (Carb) or 0.3 μM S1P (sphingosine-1-phosphate) for 1, 3, or 6 h. Total cell lysates were subject to immunoblotting for CCN1 protein and GAPDH (loading control). **, P < 0.01 versus control (n = 6). (B) Serum-starved glioblastoma cells were pretreated with 1 μg/ml C3 exoenzyme (24 h) to functionally inhibit RhoA or with 10 μM Y-27632 (1 h) to block Rho kinase (ROCK). Pretreated cells were then stimulated with 0.3 μM S1P for an additional 1 h. Total cell lysates were subject to immunoblotting for CCN1 protein and GAPDH (loading control). **, P < 0.01 versus control (n = 5).