Inhibition of PI3K or MEK inhibits LPS-induced Akt or ERK activation, respectively. Double-transduced endothelial cells (as labeled) were pretreated for 60 minutes with specific inhibitors, vehicle only, or left untreated. Cells were subsequently treated with LPS (100 ng/mL) and CHX (50 μg/mL) for 60 minutes (Akt) or 30 minutes (ERK). Activation of Akt and ERK was determined by immunoblotting for phospho-Akt or phospho-ERK, respectively. Membranes were stripped and reprobed for total levels of ERK or Akt.