p38 mitogen-activated protein kinases are a class of mitogen-activated protein kinases (MAPKs) that are responsive to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock, and are involved in cell differentiation, apoptosis and autophagy. Abnormal activity (higher or lower than physiological) of p38 has been implicated in pathological stresses in several tissues, that include neuronal, bone, lung, cardiac and skeletal muscle, red blood cells, and fetal tissues. Phospho-p38 MAPK (Tyr182), often tested alongside Thr180, is a significant biomarker for the activation state of p38 MAPK, a crucial enzyme in cellular stress and inflammatory responses. The phosphorylation at these sites, Thr180 and Tyr182, is essential for the full activation of p38 MAPK, allowing it to regulate various cellular processes in response to stress, inflammation, and other signals.