Pre-mRNA splicing enhancer elements are short RNA sequences capable of activating weak splice sites in nearby introns that are required for accurate splice site recognition and the control of alternative splicing. Splicing enhancer elements contain specific binding sites for serine/arginine (SR)-rich splicing factors, which include SC35, 9G8, SRp20 and SF2/ASF. The family of SR factors all contain one or more RNA recognition motifs (RRM) and a SR-rich domain. The SR factor family is not only essential for constitutive splicing, but also regulate splicing in a concentration-dependent manner by influencing the selection of alternative splice sites. SFRS11 (splicing factor, arginine/serine-rich 11), also known as arginine-rich 54 kDa nuclear protein (p54) or NET2, is a 484 amino acid nuclear protein that colocalizes with spliceosome components and belongs to the splicing factor SR family. SFRS11 may function in pre-mRNA splicing and contains one RRM (RNA recognition motif) domain.