We further show that inhibition of the splicing regulatory cdc2-like kinases in combination with an ERR-β agonist shifts isoform expression in favor of ERR-β2 and potentiates inhibition of growth and migration in GBM cells and intracranial tumors.-Tiek, D. M., Khatib, S. A., Trepicchio, C. J., Heckler, M. M., Divekar, S. D., Sarkaria, J. N., Glasgow, E., Riggins, R. B. Estrogen-related receptor β activation and isoform shifting by cdc2-like kinase inhibition restricts migration and intracranial tumor growth in glioblastoma.