Fig. 3.

Effect of normal and photoactivable sphingosine on proliferation and viability of cultured fibroblasts. Six hours after seeding, NPA and control fibroblasts were treated with normal (gray dotted line) or photoactivable (black dotted line) sphingosine solubilized in cell culture medium, both at the final concentration of 38 nM for up to 72 h. The proliferation and viability were compared with untreated cells (gray line). After 24, 48, and 72 h, the number of total cells (A1, B1) and of dead cells (A2 and B2, left) was evaluated by Trypan blue exclusion assay as described in Materials and Methods. Data are the means ± SD of three different experiments.