MAPK7 and glioma: Finally, intraperitoneal injection of ERK5-specific inhibitor XMD8-92 at a dose of 50 mg/kg per day delayed the xenograft growth of ERK5-overexpression tumor cells (Fig. 3Q, R), and these results further suggested that the kinase activity or some other unknown functions of ERK5 were important for glioma cell proliferation.