SWAP (suppressor of white apricot protein homolog), also known as SFRS8 (splicing factor, arginine/serine-rich 8), is the 951 amino acid human homolog of a Drosophilia splicing protein. Localized to the nucleus, SWAP contains two SURP repeats through which it is thought to mediate splicing events, possibly regulating the alternative splicing of Fibronectin and CD45RC. SWAP regulates its own expression levels (via control of splicing in its first two introns) and may act in tandem with other arginine/serine-rich splicing factors to control protein expression. The gene encoding SWAP is located on a region of chromosome 12 that is related to asthma susceptibility, possibly indicating a role for SWAP in the development of asthma. Multiple isoforms of SWAP exist due to alternative splicing events.