Alternative splicing is an evolutionarily conserved and essential cellular process that is catalyzed by a multi-complex spliceosome. Dysregulation of this process has been implicated in various tumors over the recent years. is a critical subunit of U2 small nuclear ribonucleoprotein (snRNP) in the spliceosome, which has been found to be aberrant in several human diseases. Recent reports suggest that might be a novel therapeutic target. However, a comprehensive description of is lacking. In this review, we present the findings of from protein structure, biological function to strong associations with human diseases including cancer. Studies have reported that dysregulation and associated alternative splicing events mediate tumorigenesis and other immune-related disorders. However, further functional and mechanistic studies are needed to fully understand the regulatory network of in human diseases. In conclusion, could serve as a promising prognostic biomarker and therapeutic target for specific cancer types, including prostate cancer, colorectal cancer and hepatocellular carcinoma.