MAPKAPK2 and periodontitis: However, in periodontitis, eATP secreted by A. actinomycetemcomitans induces an upregulation of cytokine expression, resulting in the massive recruitment of inflammatory cells via mainly the p38 mitogen-activated protein kinase (MAPK) and MAPK-activated protein kinase 2 (MK2) pathways (Herbert et al., 2017).