pp38 Mitogen activated protein kinases p38MAPK are a highly evolutionary conserved group of protein kinases, which are central for cell adaptation to environmental changes as well as for immune response, inflammation, tissue regeneration, and tumour formation. p38945 is the best characterized, whereas the functions of p38946, p38947 and p38948 have been less studied. The four p38MAPKs are ubiquitously expressed, although the level of expression of each isoform varies in particular tissues. Moreover, it is becoming clear that apart from common functions as stress kinases, they perform specific roles in a cell- and tissue-dependent manner, unveiling important functions in physiology and pathology.ppIn this issue we provide an updated view of the p38 signalling pathway, including new regulatory mechanisms, substrates and implication in different diseases. This issue will be of interest to basic researchers working in cell signalling and immunology, to chemical biologists interested in dru