Plays a role in constitutive splicing and can modulate the selection of alternative splice sites. Represses the splicing of MAPT/Tau exon 10. {ECO:0000269|PubMed:10196175, ECO:0000269|PubMed:11875052, ECO:0000269|PubMed:12024014, ECO:0000269|PubMed:12604611, ECO:0000269|PubMed:15009090, ECO:0000269|PubMed:15009664, ECO:0000269|PubMed:15695522, ECO:0000269|PubMed:7556075}. This is the function of SRSF9 (serine and arginine rich splicing factor 9, Ensembl gene identifier ENSG00000111786).