SRSF1, also known as Serine/arginine-rich splicing factor 1, is a member of the arginine/serine-rich splicing factor protein family, and functions in both constitutive and alternative pre-mRNA splicing. This protein binds to pre-mRNA transcripts and components of the spliceosome, and can either activate or repress splicing depending on the location of the pre-mRNA binding site. The protein's ability to activate splicing is regulated by phosphorylation and interactions with other splicing factor associated proteins. In addition to being involved in the splicing process, it also mediates post-splicing activities, such as mRNA nuclear export and translation.