Regulation of human mitogen‐activated protein kinase 15 (extracellular signal‐regulated kinase 7/8) and its functions: A recent update

Mitogen‐activated protein kinase 15 (MAPK15), originally also known as extracellular signal‐regulated kinase 7/8, is the most recently identified atypical MAPK and the least studied so far. Examinations of the role of MAPK15 in various cell lines and model systems indicate that MAPK15 participates in a variety of cellular activities such as promoting cell proliferation, cell transformation, and apoptosis; stimulating autophagy; regulating cell division, ciliogenesis, and protein secretion; and maintaining genome stability. As multiple roles of MAPK15 were observed among these studies, therefore, it remains unclear whether MAPK15 acts as a proto‐oncogene or tumor suppressor. Here, the recent literature on human MAPK15 and the resulting functions will be discussed. Over the past decades, despite the fact that in‐depth investigations have been done on typical mitogen‐activated protein kinases (MAPKs), the atypical MAPKs (especially MAPK15, also known as extracellular signal‐regulated kinase 7/8 [ERK7/8]), remain relatively understudied, in which there are still a lot of unanswered questions for the cellular functions. Since its discovery in the year of 1999, no exhaustive review has yet been conducted to enhance our understanding of MAPK15. In this review, we summarized the literature of all known functions reported on human MAPK15 and also discussed its potential as a druggable target.