MAPK4 and urinary bladder cancer: For example, circ-MAPK4 suppresses apoptosis in malignant glioma through regulation of miR-125a-3p which influences the MAPK signaling pathway19; circ-LMTK2 accelerates the proliferation and metastasis of gastric cancer by targeting miR-150-5p20; and circ-ZKSCAN1 inhibits bladder cancer progression by regulating the miR-1178-3p/p21 axis21.