Our recent phosphoproteomic analysis of GSK-3 substrates identified multiple core splicing factors implicated in MDS and AML (19, 22), consistent with prior studies supporting the importance of GSK-3 in splicing regulation, including evidence that GSK-3 phosphorylation of SRSF2 regulates splicing of MAPT (Tau) exon 10 (23–25). This evidence concerns the gene SRSF2 and myelodysplastic syndrome.