Inhibition of MEK blocks GRP78 up-regulation and enhances apoptosis induced by ER stress in gastric cancer cells.

We studied potential interactions between the endoplasmic reticulum (ER) stress response and the MEK/ERK pathway. Induction of ER stress did not trigger significant apoptosis, but caused rapid activation of ERK1/2 in gastric cancer cells. Inhibition of MEK enhanced ER stress-induced apoptosis via a caspase-dependent, mitochondria-mediated mechanism.