Development of the cerebral cortex involves many phases, including neural stem cell proliferation, neuronal migration, and differentiation. Defects in these phases lead to malformations in cortical development (MCDs). For example, disruption in neuronal migration causes lissencephaly, a form of MCD characterized by a smooth brain surface. Mutations in a number of genes, such as PAFAH1B1 (aka LIS1), DCX, TUBA1A, ARX, and DYNC1H1, are common causes behind lissencephaly. Many of those genes are involved in microtubule assembly and stabilization during neuronal migration. Recently, mutations in MAST1 (microtubule associated serine/threonine kinase 1) were found to cause mega-corpus-callosum syndrome with cerebellar hypoplasia and cortical malformations (MCC-CH-CM). MAST1 interacts with microtubules in microtubule associated proteins (MAPs)-dependent manner. Moreover, in our MCD patient, we identified a novel MAST1 mutation using whole exome sequencing (WES). By in utero electroporation, we observed that MAST1 knockdown in mouse embryos inhibited neuronal migration but not cell fate, while overexpressing wild-type MAST1 and its various mutants do not show abnormalities. MAST1 mutations reduced protein expression level in Hek293 cell lines compared to wild-type MAST1. The reduction of its expression level might be regulated by decreasing of the stability of protein. Moreover, the various MAST1 mutants showed disruption on microtubule organization and dynamics. Further study of MAST1 role in regulating neuronal migration will be focused on the function of MAST1 domains and interaction with other genes that also interact with microtubule. Together, this study could reveal important molecular mechanisms that regulate microtubule dynamics and neuronal migration and differentiation during cortical development.