CDK5 also phosphorylated DRP1 at Ser616 to increase mitochondrial fission in brain tumor initiating cells (BTIC), while Ca2+ calmodulin-dependent protein kinase 2 (CAMK2) phosphorylated DRP1 at Ser637, inducing mitochondrial fusion in non-BTIC tumor. The gene discussed is CDK5; the disease is brain neoplasm.