SAPK2/p38 is activated by CA-4-P and regulates membrane blebbing.

(A) Sparse or confluent endothelial cultures were treated with 1 μM CA-4-P, cell lysates were harvested, and equal amounts of protein were analyzed by Western blotting for phospho–SAPK-2/p38 (P-p38). (B,C) Confluent endothelial cells were preincubated with vehicle control (B) or SB203580 (30 minutes, 10 μM; C) and then were exposed to CA-4-P (60 minutes, 1 μM). Cells were stained for actin with Texas Red–conjugated phalloidin as described in “Materials and methods” section and were examined by fluorescence microscopy. Bar = 35 μm.