In the developing and matured central nervous system, post-transcriptional gene regulations (including RNA splicing, microRNA biogenesis, editing, stability, translation, and transport) are likely to play important roles, in terms of Stem/progenitor cell maintenance, neuronal differentiation, acquisition of ion channel diversity and synaptic plasticity. To demonstrate these issues, we are studying the following neural RNA-binding proteins, including Musashi, Elavl families by using both in vitro and in vivo approaches. Here, we wish to introduce tour current understanding of post-transcriptional control in development and stem cells of the evolutionarily conserved, neural RNA-binding protein Musashi, which is an RNA-binding protein that has two tandem RNA-recognition motifs (RRM-1 and RRM-2), each of which includes two short, highly conserved motifs (Okano et al., J Cell Sci, 2002). In our previuss studies, we showed that, in mammals, Musashi-1 activates the self-renewal of neural stem cells by the augmentation of Notch signaling through translational repression of m-Numb mRNA. So far, we have found that various target mRNAs, including m-Numb, PTEN, and Robo3 mRNAs (Imai et al., Mol Cell Biol, 2001; Muto et al., PLoS ONE, 2012; Kuwako et al., Neuron, 2010), are translationally regulated by Musashi-1. However, Musashi-1's function is not limited to these translational regulations. Recently, we tried to reveal Novel Functions of Musashi1 by using High through-put sequencing in vivo UV crosslinked immunoprecipitaition (HITS-CLIP) analysis. Transcriptome-wide map of Msi1-RNA interaction by HITS-CLIP identified lots of in vivo bona-fide Msi1 targets in the brain and uncovered novel functions of Musashi-1 in alternative splicing, miRNA processing, translational regulation and etc.