Caspases involved in ER stress-mediated cell death.

Caspases are cysteine proteases involved in apoptotic pathways. Excess endoplasmic reticulum (ER) stress, induced by the accumulation of unfolded or malfolded proteins, activates various apoptotic pathways. Crosstalk between the mitochondria and ER plays an essential role in ER stress-mediated cell death. The cytochrome c-dependent apoptotic pathway is activated by ER stress. On the other hand, caspase-12, which is located at the ER, is also activated by excess ER stress and results in cell death in the absence of the cytochrome c-dependent pathway. The predominant apoptotic pathway may differ among cell type and differentiation stage.