In order to gain insights on how mutations in SRSF2, one of the splicing factors mutated in MDS patients, affect splicing, we have prepared the SRSF2 mutant cDNAs carrying three kinds of mutations at 95th position of Proline residue (P95H, L and R) found in MDS patients. The gene discussed is SRSF2; the disease is myelodysplastic syndrome.