In glioma, circ-MAPK4 affects cell proliferation and apoptosis by functioning as a miR-125a-3p sponge to activate p38/MAPK signaling pathway [195]; circular RNA Pleiotrophin (circ_PTN) promotes proliferation and carcinogenesis through modulating miR-122/SOX6 axis to activate MAPK/ERK pathway [196]; circ-TLK1 facilitates cell proliferation and tumor growth by sponging miR-17-5p to target PANX1/MAPK/ERK axis [197]. Here, MAPK4 is linked to central nervous system cancer.