FIGURE 2.
S1P and 5.3 dynes/cm2 WSS synergistically activate calpains and increase EC invasion. EC monolayers seeded on collagen matrices were subjected to the indicated magnitudes of WSS in the absence or presence of S1P for 6 (A and C) or 18 h (B and D). The cultures were then either lysed to measure calpain activity (A and C) or used to quantify the average number of invading cells (B and D). As described under “Experimental Procedures,” calpain activation was recorded as relative fluorescence units (mean ± S.D.; n = 3) using the Calpain-GloTM protease assay kit. Western blot analyses were performed with antibodies directed to GAPDH to verify equal loading between samples (not shown). Each data point (mean ± S.D.) was derived by averaging band intensities from three experiments. *, p < 0.05 and **, p < 0.01 versus no S1P and no WSS treatment; ‡, p < 0.05 and ‡‡, p < 0.01 versus all other treatments. dyn, dynes.