By freeing introns from the need to splice themselves, the spliceosome would in effect have encouraged introns to prolif剪接体的出现让插入子不再需要自行剪接，结果等于鼓励插入子增生、突变与演化。
Four short nucleotide sequences within introns serve as signals that indicate to the spliceosome where to cut [see box o在插入子的序列上，有四个简短的核苷酸序列，标示了剪接体下刀的位置（参见本页左方〈细胞的剪接机器〉）。