RNA binding protein that regulates the expression of target mRNAs at the translation level. Regulates expression of the NOTCH1 antagonist NUMB. Binds RNA containing the sequence 5'-GUUAGUUAGUUAGUU-3' and other sequences containing the pattern 5'-[GA]U(1-3)AGU-3'. May play a role in the proliferation and maintenance of stem cells in the central nervous system (By similarity). Expressed in stem and progenitor cells in the subventricular zone of the hippocampus (at protein level) (PubMed:16554442). Detected throughout the hippocampus (PubMed:12205668). Detected in astrocytes, ependymal cells and in the anterior subventricular zone. Detected in proliferating cells (PubMed:12205668). Up-regulated in the CA1 region of the hippocampus after ischemia. The first RNA recognition motif binds more strongly to RNA compared to the second one. Belongs to the Musashi family.