The human genome sequence has been decoded, and the more complicated regulation of gene function is revealed in the post-genome era. In the various mechanisms of epigenome, RNA dramatically controls gene expression through the various post-transcriptional processing including transcription, splicing, cap addition, polyadenylation, nuclear export, translation. Especially, the alternative splicing is involved in all of those post-transcriptional regulations, as well as splicing of pre-mRNA. However, there were few reports, how the alternative splicing contributes to the regulations of cellular functions because of its difficulty of the analysis. This review discusses the molecular mechanism of alternative splicing and its regulator ; Serine/arginine-rich splicing factor （SRSF）. We also discuss how the SRSF genes sustain their own proper expressions and functions
