Effect of anastellin and endostatin on ERK and p38 MAP kinase activity. Micro-vessel cell monolayers were treated with the indicated doses of either anastellin or endostatin for 1 hour (A) or treated with 20 μM anastellin or 0.5 μM endostatin for the indicated time (B). Cell layers were washed twice with ice-cold PBS containing 1 mM Na3VO4, solubilized in gel sample buffer. Cell lysates were prepared and analyzed by Western blot for phospho-ERK and phospho-p38 MAP kinase. Blots were then stripped and reprobed for either total ERK as a loading control. Additional controls indicated no change in the levels of p38 (data not shown).