p38 MAPK is a type of protein kinase that plays a crucial role in cellular responses to stress, inflammation, and other stimuli. It is part of the MAPK (mitogen-activated protein kinase) signaling pathway, which helps regulate various cellular processes, including growth, differentiation, and apoptosis (programmed cell death). This protein is activated by various stress signals, such as cytokines and environmental stressors, leading to a cascade of reactions within the cell. By influencing gene expression and protein activity, p38 MAPK helps cells adapt to changing conditions and maintain homeostasis, making it important in both health and disease.