Since the 78 kDa glucose-regulated protein (GRP78) is a key marker of endoplasmic reticulum (ER) stress, we investigated and analyzed GRP78 expression levels in the trabecular meshwork (TM) by eyes with primary open angle glaucoma (POAG) and normal eyes to understand the role of GRP78 in human TM cells apoptosis. The gene discussed is HSPA5; the disease is open-angle glaucoma.