Abstract: Musashi is a family of RNA binding proteins with a conservative evolution. This protein family is selectively expressed in the nervous system and comprises two members, namely, Musashi-1 and Musashi-2. Musashi-1 and Musashi-2 are translational suppressors of Numb mRNA and can synergistically regulate the Notch signaling pathway; as a result, an asymmetric division of stem cells occurs. Musashi-1 is the first member of the family and was originally isolated from Drosophila. As a candidate stem gene, Musashi-1 participates in disease progression in stem cells. Musashi-1 is also an important protein that maintains the functions of stem cells, participates in tumor-related signaling pathways, and participates in cell proliferation and apoptosis. Furthermore, Musashi-1 is overexpressed in many solid tumors, such as neuroglioma, esophagus, gastric, colorectal, and breast cancers. Studies on Musashi-1 can provide new insights into genetic diagnosis and cancer treatments. In this study, the structure and function of Musashi-1 and the research progress of tumor mechanisms were summarized and reviewed.