MAPK13 and neoplasm: Regarding its functionality as a tumor suppressor, p38δ-expression knockdown has been shown to increase proliferation and tumorigenicity of cancer cells, such as glioma, melanoma, and oesophageal SCC, one of the pathways by which p38δ is silenced in melanoma and OESCC is the hypermethylation and inhibition of the transcription of its MAPK13 gene [69,70,111,112].