Musashi 1, a neural RNA-binding protein, plays an important role in regulating cell differentiation in precursor cells. Musashi 1 (Msi-1) has been shown to increase the accumulation of tau isoforms in intracellular inclusions in dementia and Parkinsons. The presence of Msi-1 in a significant percentage of neurons containing cytoplasmic inclusions in 2 other neurodegenerative diseases Alzheimers disease and Pick disease suggests that it may play a role in the pathogenesis of these neurodegenerative disorders. Musashi 1 has also been detected in human tumor tissues such as gliomas and melanomas, suggesting its involvement in cancer development. Msi-1 also appears to play be an vital role in the development of several types of carcinoma such as human hepatoma, and may be a useful molecular marker for tumor detection.