O4I1 is primarily utilized in research settings as a selective inhibitor of the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). It plays a significant role in studying the unfolded protein response (UPR) pathway, which is crucial for understanding cellular stress responses and protein homeostasis. By inhibiting PERK, O4I1 helps researchers investigate the mechanisms of apoptosis, autophagy, and cell survival under stress conditions, particularly in cancer biology and neurodegenerative diseases. Its application extends to exploring potential therapeutic strategies for conditions linked to endoplasmic reticulum stress, such as certain cancers and Alzheimer's disease. Additionally, O4I1 is used in pharmacological studies to assess the effects of PERK inhibition on tumor growth and drug resistance, providing insights into targeted cancer therapies.