Pre-mRNA splicing reaction occurs in a large ribonucleoprotein complex called the spliceosome. After the splicing reaction, the spliceosome is disassembled to release the splicing products including spliced mRNA. Here we show that protein factors in a HeLa nuclear extract or a DEAE-cellulose fraction as well as ATP are required to release the splicing products form the spliceosome in which the splicing reaction has already completed.