SRSF1 and breast cancer: During the process of tumor recurrence and metastasis, alternative splicing plays a crucial role.[7] For example, SF3B1 is a subunit of the spliceosome factor 3b complex, and its mutations promote malignancy and result in poor prognosis.[8] SRSF1, which is a serine/arginine‐rich protein, is another oncogenic splicing factor, and overexpressed in breast cancer.