Jun N-terminal Kinase (JNK) is a type of protein kinase that plays a crucial role in cellular signaling. It is part of the Mitogen-Activated Protein Kinase (MAPK) pathway, which helps cells respond to various stressors, such as inflammation and environmental changes. JNK is involved in regulating processes like cell growth, differentiation, and apoptosis (programmed cell death). JNK is activated by various stimuli, including cytokines and stress signals, leading to the phosphorylation of target proteins. This activation can influence gene expression and cellular responses, making JNK important in conditions like cancer, neurodegenerative diseases, and diabetes. Understanding JNK's functions can help in developing therapeutic strategies for these diseases.