Whereas JNK has been shown to play a pivotal role in CSC maintenance in various human cancers (28, 29, 30, 31, 32, 33, 34), the role of MKP-1 in CSCs, in contrast, remains mostly unclear, except that two recent studies reported that high MKP-1 expression is associated with the loss of stemness in glioma stem cells (46, 47). This evidence concerns the gene MAPK8 and cancer.