Tubulin-binding protein that acts as a negative regulator of Notch signaling pathway. Shuttles between the cytoplasm and the nucleus and mediates the nuclear export of RBPJ/RBPSUH, thereby preventing the interaction between RBPJ/RBPSUH and NICD product of Notch proteins (Notch intracellular domain), leading to down-regulate Notch-mediated transcription. May play a role in neurogenesis.