Abstract
Neuroblastomas are associated with KIF1Bβ mutations within tumor suppressor region 1p36. In this issue of Developmental Cell, Li et al. (2016) show that KIF1Bβ binding releases calcineurin autoinhibition, leading to dephosphorylation of the DRP1 GTPase and subsequent mitochondrial fragmentation. KIF1Bβ impairment causes mitochondrial hyperfusion, impairing developmental apoptosis and promoting tumorigenesis.